Parameters¶

Usage¶

wannier90.x can be run in parallel using MPI libraries to reduce the computation time.

For serial execution use: wannier90.x [-pp] [seedname]

seedname: If a seedname string is given the code will read its input from a file seedname.win. The default value is wannier. One can also equivalently provide the string seedname.win instead of seedname.
-pp: This optional flag tells the code to generate a list of the required overlaps and then exit. This information is written to the file seedname.nnkp.

For parallel execution use: mpirun -np NUMPROCS wannier90.x [-pp] [seedname]

NUMPROCS: substitute with the number of processors that you want to use.

Note that the mpirun command and command-line flags may be different in your MPI implementation: read your MPI manual or ask your computer administrator.

Note also that this requires that the wannier90.x executable has been compiled in its parallel version (follow the instructions in the file README.install in the main directory of the wannier90 distribution) and that the MPI libraries and binaries are installed and correctly configured on your machine.

`seedname.win` File¶

The wannier90 input file seedname.win has a flexible free-form structure.

The ordering of the keywords is not significant. Case is ignored (so num_bands is the same as Num_Bands). Characters after !, or # are treated as comments. Most keywords have a default value that is used unless the keyword is given in seedname.win. Keywords can be set in any of the following ways

num_wann 4
num_wann = 4
num_wann : 4

A logical keyword can be set to true using any of the following strings: T, true, .true..

For further examples see Section 10.1{reference-type="ref" reference="winfile"} and the the wannier90 Tutorial.

Keyword List¶

    Keyword        Type  Description

System Parameters
num_wann I Number of WF num_bands I Number of bands passed to the code unit_cell_cart P Unit cell vectors in Cartesian coordinates atoms_cart * P Positions of atoms in Cartesian coordinates atoms_frac * R Positions of atoms in fractional coordinates with respect to the lattice vectors mp_grid I Dimensions of the Monkhorst-Pack grid of k-points kpoints R List of k-points in the Monkhorst-Pack grid gamma_only L Wavefunctions from underlying ab initio calculation are manifestly real spinors L WF are spinors shell_list I Which shells to use in finite difference formula search_shells I The number of shells to search when determining finite difference formula skip_B1_tests L Check the condition B1 of Ref. ¹ nnkpts I Explicit list of nearest-neighbour k-points. kmesh_tol R The tolerance to control if two kpoint belong to the same shell

seedname.win file keywords defining the system. Argument types are represented by, I for a integer, R for a real number, P for a physical value, L for a logical value and S for a text string.\ * atoms_cart and atoms_frac may not both be defined in the same input file. ::: :::

::: center ::: {#parameter_keywords2}

     Keyword          Type  Description

   Job Control              
  postproc_setup       L    To output the `seedname.nnkp` file
  exclude_bands        I    List of bands to exclude from the calculation
select_projections     I    List of projections to use in Wannierisation
 auto_projections      L    To automatically generate initial projections
     restart           S    Restart from checkpoint file
      iprint           I    Output verbosity level
   length_unit         S    System of units to output lengths
  wvfn_formatted       L    Read the wavefunctions from a (un)formatted file
       spin            S    Which spin channel to read
    devel_flag         S    Flag for development use
   timing_level        I    Determines amount of timing information written to output
   optimisation        I    Optimisation level

translate_home_cell L To translate final Wannier centres to home unit cell when writing xyz file write_xyz L To write atomic positions and final centres in xyz file format write_vdw_data L To write data for futher processing by w90vdw utility write_hr_diag L To write the diagonal elements of the Hamiltonian in the Wannier basis to seedname.wout (in eV)

seedname.win file keywords defining job control. Argument types are represented by, I for a integer, R for a real number, P for a physical value, L for a logical value and S for a text string. translate_home_cell only relevant if write_xyz is .true. ::: :::

::: center ::: {#parameter_keywords4}

        Keyword             Type  Description

Disentanglement Parameters
dis_win_min P Bottom of the outer energy window dis_win_max P Top of the outer energy window dis_froz_min P Bottom of the inner (frozen) energy window dis_froz_max P Top of the inner (frozen) energy window dis_froz_proj L To activate projectability disentanglement dis_proj_min P Lower threshold for projectability disentanglement dis_proj_max P Upper threshold for projectability disentanglement dis_num_iter I Number of iterations for the minimisation of \(\Omega_{\mathrm{I}}\) dis_mix_ratio R Mixing ratio during the minimisation of \(\Omega_{\mathrm{I}}\) dis_conv_tol R The convergence tolerance for finding \(\Omega_{\mathrm{I}}\) dis_conv_window I The number of iterations over which convergence of \(\Omega_{\mathrm{I}}\) is assessed. dis_spheres_num I Number of spheres in k-space where disentaglement is performed dis_spheres_first_wann I Index of the first band to be considered a Wannier function dis_spheres R List of centres and radii, for disentanglement only in spheres

seedname.win file keywords controlling the disentanglement. Argument types are represented by, I for a integer, R for a real number, P for a physical value, L for a logical value and S for a text string. ::: :::

::: center ::: {#parameter_keywords5}

      Keyword          Type  Description

Wannierise Parameters
num_iter num_cg_steps conv_window conv_tol precond conv_noise_amp conv_noise_num num_dump_cycles num_print_cycles write_r2mn guiding_centres num_guide_cycles num_no_guide_iter trial_step * fixed_step * use_bloch_phases ** site_symmetry*** symmetrize_eps*** slwf_num slwf_constrain slwf_lambda slwf_centres I Number of iterations for the minimisation of \(\Omega\) I During the minimisation of \(\Omega\) the number of Conjugate Gradient steps before resetting to Steepest Descents I The number of iterations over which convergence of \(\Omega\) is assessed P The convergence tolerance for finding \(\Omega\) L Use preconditioning R The amplitude of random noise applied towards end of minimisation procedure I The number of times random noise is applied I Control frequency of check-pointing I Control frequency of printing L Write matrix elements of \(r^2\) between WF to file L Use guiding centres I Frequency of guiding centres I The number of iterations after which guiding centres are used R The trial step length for the parabolic line search during the minimisation of \(\Omega\) R The fixed step length to take during the minimisation of \(\Omega\), instead of doing a parabolic line search L To use phases for initial projections L To construct symmetry-adapted Wannier functions R The convergence tolerance used in the symmetry-adapted mode I The number of objective WFs for selective localization L Whether to constrain the centres of the objective WFs R Value of the Lagrange multiplier for constraining the objective WFs P The centres to which the objective WFs are to be constrained

seedname.win file keywords controlling the wannierisation. Argument types are represented by, I for a integer, R for a real number, P for a physical value, L for a logical value and S for a text string. * fixed_step and trial_step may not both be defined in the same input file. **Cannot be used in conjunction with disentanglement. ***Cannot be used in conjunction with the inner (frozen) energy window. ::: :::

::: {#parameter_keywords6}

               Keyword                    Type  Description

           Plot Parameters                      
             wannier_plot                  L    Plot the WF
          wannier_plot_list                I    List of WF to plot
        wannier_plot_supercell             I    Size of the supercell for plotting the WF
         wannier_plot_format               S    File format in which to plot the WF
          wannier_plot_mode                S    Mode in which to plot the WF, molecule or crystal
         wannier_plot_radius               R    Cut-off radius of WF\*
          wannier_plot_scale               R    Scaling parameter for cube files
       wannier_plot_spinor_mode            S    Quantity to plot for spinor WF
      wannier_plot_spinor_phase            L    Include the "phase" when plotting spinor WF
              bands_plot                   L    Plot interpolated band structure
             kpoint_path                   P    K-point path for the interpolated band structure
           bands_num_points                I    Number of points along the first section of the k-point path
          bands_plot_format                S    File format in which to plot the interpolated bands
          bands_plot_project               I    WF to project the band structure onto
           bands_plot_mode                 S    Slater-Koster type interpolation or Hamiltonian cut-off
            bands_plot_dim                 I    Dimension of the system
          fermi_surface_plot               L    Plot the Fermi surface
       fermi_surface_num_points            I    Number of points in the Fermi surface plot
             fermi_energy                  P    The Fermi energy
           fermi_energy_min                P    Lower limit of the Fermi energy range
           fermi_energy_max                P    Upper limit of the Fermi energy range
          fermi_energy_step                R    Step for increasing the Fermi energy in the specified range
      fermi_surface_plot_format            S    File format for the Fermi surface plot
    [hr_plot]{style="color: red"}          L    [This parameter is not used anymore. Use write_hr instead.]{style="color: red"}
   [write_hr]{style="color: blue"}         L    [Write the Hamiltonian in the WF basis]{style="color: blue"}
  [write_rmn ]{style="color: blue"}        L    [Write the position operator in the WF basis]{style="color: blue"}
  [write_bvec ]{style="color: blue"}       L    [Write to file the matrix elements of the bvectors and their weights]{style="color: blue"}
   [write_tb ]{style="color: blue"}        L    [Write lattice vectors, Hamiltonian, and position operator in WF basis]{style="color: blue"}
              hr_cutoff                    P    Cut-off for the absolute value of the Hamiltonian
             dist_cutoff                   P    Cut-off for the distance between WF
           dist_cutoff_mode                S    Dimension in which the distance between WF is calculated
       translation_centre_frac             R    Centre of the unit cell to which final WF are translated

[use_ws_distance ]{style="color: blue"} L [Improve interpolation using minimum distance between WFs, see Chap. [chap:interpolation]]{style="color: blue"} [ws_distance_tol ]{style="color: blue"} R [Absolute tolerance for the distance to equivalent positions.]{style="color: blue"} [ws_search_size ]{style="color: blue"} I [Maximum extension in each direction of the super-cell of the Born-von Karmann cell to search for points inside the Wigner-Seitz cell]{style="color: blue"} [write_u_matrices ]{style="color: blue"} L [Write \(\mathbf{U}^{(\mathbf{k})}\) and \(\mathbf{U}^{\mathrm{dis}(\mathbf{k})}\) matrices to files]{style="color: blue"}

seedname.win file keywords controlling the plotting. Argument types are represented by, I for a integer, R for a real number, P for a physical value, L for a logical value and S for a text string. * Only applies when wannier_plot_format is cube. :::

::: center ::: {#parameter_keywords7}

       Keyword            Type  Description

 Transport Parameters           
      transport            L    Calculate quantum conductance and density of states
    transport_mode         S    Bulk or left-lead_conductor_right-lead calculation
     tran_win_min          P    Bottom of the energy window for transport calculation
     tran_win_max          P    Top of the energy window for transport calculation
   tran_energy_step        R    Sampling interval of the energy values
     fermi_energy          R    The Fermi energy
     tran_num_bb           I    Size of a bulk Hamiltonian
     tran_num_ll           I    Size of a left-lead Hamiltonian
     tran_num_rr           I    Size of a right-lead Hamiltonian
     tran_num_cc           I    Size of a conductor Hamiltonian
     tran_num_lc           I    Number of columns in a left-lead_conductor Hamiltonian
     tran_num_cr           I    Number of rows in a conductor_right-lead Hamiltonian
   tran_num_cell_ll        I    Number of unit cells in PL of left lead
   tran_num_cell_rr        I    Number of unit cells in PL of right lead
    tran_num_bandc         I    Half-bandwidth+1 of a band-diagonal conductor Hamiltonian
    tran_write_ht          L    Write the Hamiltonian for transport calculation
     tran_read_ht          L    Read the Hamiltonian for transport calculation
  tran_use_same_lead       L    Left and right leads are the same
 tran_group_threshold      R    Distance that determines the grouping of WFs
      hr_cutoff            P    Cut-off for the absolute value of the Hamiltonian
     dist_cutoff           P    Cut-off for the distance between WF
   dist_cutoff_mode        S    Dimension in which the distance between WF is calculated
     one_dim_axis          S    Extended direction for a one-dimensional system

translation_centre_frac R Centre of the unit cell to which final WF are translated

seedname.win file keywords controlling transport. Argument types are represented by, I for a integer, R for a real number, P for a physical value, L for a logical value and S for a text string. ::: :::

System¶

`integer :: num_wann`¶

Number of WF to be found.

No default.

`integer :: num_bands`¶

Total number of bands passed to the code in the seedname.mmn file.

Default num_bands=num_wann

Cell Lattice Vectors¶

The cell lattice vectors should be specified in Cartesian coordinates.

begin unit_cell_cart\ [units] \(\(\begin{array}{ccc} A_{1x} & A_{1y} & A_{1z} \\ A_{2x} & A_{2y} & A_{2z} \\ A_{3x} & A_{3y} & A_{3z} \end{array}\)\) end unit_cell_cart

Here \(A_{1x}\) is the \(x\)-component of the first lattice vector \(\mathbf{A}_1\), \(A_{2y}\) is the \(y\)-component of the second lattice vector \(\mathbf{A}_2\), etc.

[units] specifies the units in which the lattice vectors are defined: either Bohr or Ang.

The default value is Ang.

Ionic Positions¶

The ionic positions may be specified in fractional coordinates relative to the lattice vectors of the unit cell, or in absolute Cartesian coordinates. Only one of atoms_cart and atoms_frac may be given in the input file.

Cartesian coordinates¶

begin atoms_cart\ [units] \(\(\begin{array}{cccc} P & R^{P}_{x} & R^{P}_{y} & R^{P}_{z} \\ Q & R^{Q}_{x} & R^{Q}_{y} & R^{Q}_{z} \\ \vdots \end{array}\)\) end atoms_cart

The first entry on a line is the atomic symbol. The next three entries are the atom's position \(\mathbf{R}=(R_x , R_y, R_z)\) in Cartesian coordinates. The first line of the block, [units], specifies the units in which the coordinates are given and can be either bohr or ang. If not present, the default is ang.

Fractional coordinates¶

begin atoms_frac \(\(\begin{array}{cccc} P & F^{P}_{1} & F^{P}_{2} & F^{P}_{3} \\ Q & F^{Q}_{1} & F^{Q}_{2} & F^{Q}_{3} \\ \vdots \end{array}\)\) end atoms_frac

The first entry on a line is the atomic symbol. The next three entries are the atom's position in fractional coordinates \(\mathbf{F} = F_1 \mathbf{A}_{1} + F_2 \mathbf{A}_{2} + F_3 \mathbf{A}_{3}\) relative to the cell lattice vectors \(\mathbf{A}_i\), \(i\in [1,3]\).

`integer, dimension :: mp_grid(3)`¶

Dimensions of the regular (Monkhorst-Pack) k-point mesh. For example, for a \(2\times2\times2\) grid:

mp_grid : 2 2 2

No default.

K-points¶

Each line gives the coordinate \(\mathbf{K}=K_1 \mathbf{B}_{1} + K_2 \mathbf{B}_{2} + K_3 \mathbf{B}_3\) of a k-point in relative (crystallographic) units, i.e., in fractional units with respect to the primitive reciprocal lattice vectors \(\mathbf{B}_{i}\), \(i \in [1,3]\). The position of each k-point in this list assigns its numbering; the first k-point is k-point 1, the second is k-point 2, and so on.

begin kpoints\ \(\(\begin{array}{ccc} K^{1}_{1} & K^{1}_{2} & K^{1}_{3} \\ K^{2}_{1} & K^{2}_{2} & K^{2}_{3} \\ \vdots \end{array}\)\) end kpoints

There is no default.

Note: There is an utility provided with wannier90, called kmesh.pl, which helps to generate the explicit list of \(k\) points required by wannier90. See Sec. 1.1{reference-type="ref" reference="sec:kmesh"}.

`logical :: gamma_only`¶

If gamma_only=true, then wannier90 uses a branch of algorithms for disentanglement and localisation that exploit the fact that the Bloch eigenstates obtained from the underlying ab initio calculation are manifestly real. This can be the case when only the \(\Gamma\)-point is used to sample the Brillouin zone. The localisation procedure that is used in the \(\Gamma\)-only branch is based on the method of Ref. ².

The default value is false.

`logical :: spinors`¶

If spinors=true, then wannier90 assumes that the WF correspond to singularly occupied spinor states and num_elec_per_state=1.

The default value is false.

Shells¶

The MV scheme requires a finite difference expression for \(\nabla_{\bf k}\) defined on a uniform Monkhorst-Pack mesh of k-points. The vectors \(\{{\bf b}\}\) connect each mesh-point \({\bf k}\) to its nearest neighbours. \(N_{\mathrm{sh}}\) shells of neighbours are included in the finite-difference formula, with \(M_s\) vectors in the \(s^{\mathrm{th}}\) shell. For \(\nabla_{{\bf k}}\) to be correct to linear order, we require that the following equation is satisfied (Eq. B1 of Ref. ¹): \(\(\label{eq:B1} \sum_{s}^{N_{\mathrm{sh}}} w_s \sum_i^{M_{\mathrm{s}}} b_{\alpha}^{i,s} b_{\beta}^{i,s} = \delta_{\alpha\beta}\:,\)\) where \({\bf b}^{i,s}\), \(i\in[1,M_s]\), is the \(i^{\mathrm{th}}\) vector belonging to the \(s^{\mathrm{th}}\) shell with associated weight \(w_s\), and \(\alpha\) and \(\beta\) run over the three Cartesian indices.

`integer :: shell_list(:)`¶

shell_list is vector listing the shells to include in the finite difference expression. If this keyword is absent, the shells are chosen automatically.

`integer :: search_shells`¶

Specifies the number of shells of neighbours over which to search in attempting to determine an automatic solution to the B1 condition Eq. [eq:B1]. Larger values than the default may be required in special cases e.g. for very long thin unit cells.

The default value is 36.

`logical :: skip_B1_tests`¶

If set to .true., does not check the B1 condition Eq. [eq:B1]. This should only be used if one knows why the B1 condition should not be verified. A typical use of this flag is in conjunction with the Z2PACK code: http://www.physics.rutgers.edu/z2pack/.

The default value is .false..

`integer, dimension(:, 5) :: nnkpts`¶

Specifies the nearest-neighbour k-points which are written to the .nnkp file. This can be used to explicitly specify which overlap matrices should be calculated.

begin nnkpts
1   2   0  0  0
.
.
end nnkpts

Each nearest neighbour \(\mathbf{k + b}\) is given by a line of 5 integers. The first specifies the k-point number nkp of \(\mathbf{k}\). The second is the k-point number of the neighbour. The final three integers specify the reciprocal lattice vector which brings the k-point specified by the second integer to \(\mathbf{k + b}\).

This format is the same as in the .nnkp file, except that the number of neighbours per k-point is not specified. However, the number of neighbours still needs to be a multiple of the number of k-points.

This input parameter can be used only if postproc_setup = .true., and is not intended to be used with a full Wannier90 run. It can be used also if the k-points do not describe a regular mesh.

`real(kind=dp) :: kmesh_tol`¶

Two kpoints belong to the same shell if the distance between them is less than kmesh_tol. Units are Ang.

The default value is 0.000001 Ang.

Projection¶

The projections block defines a set of localised functions used to generate an initial guess for the unitary transformations. This data will be written in the seedname.nnkp file to be used by a first-principles code.

begin projections\ .\ .\ end projections

If guiding_centres=true, then the projection centres are used as the guiding centres in the Wannierisation routine.

For details see Section 3.1{reference-type="ref" reference="sec:proj"}.

Job Control¶

`logical :: postproc_setup`¶

If postproc_setup=true, then the wannier code will write seedname.nnkp file and exit. If wannier90 is called with the option -pp, then postproc_setup is set to true, over-riding its value in the seedname.win file.

The default value is false.

`integer :: iprint`¶

This indicates the level of verbosity of the output from 0 ("low"), the bare minimum, to 3 ("high"), which corresponds to full debugging output.

The default value is 1.

`integer :: optimisation`¶

This indicates the level of optimisation used in the code. This is a trade between speed and memory. A positive number indicates fastest execution time at the cost of more memory. Zero or negative numbers indicates a smaller memory footprint - at increased execution time.

At the moment the only values that have an effect are optimisation<=0 (low memory) and optimisation>0 (fast)

The default value is 3.

`character(len=20) :: length_unit`¶

The length unit to be used for writing quantities in the output file seedname.wout.

The valid options for this parameter are:

Ang (default)
Bohr

`character(len=50) :: devel_flag`¶

Not a regular keyword. Its purpose is to allow a developer to pass a string into the code to be used inside a new routine as it is developed.

No default.

`integer :: exclude_bands(:)`¶

A k-point independent list of states to excluded from the calculation of the overlap matrices; for example to select only valence states, or ignore semi-core states. This keyword is passed to the first-principles code via the seedname.nnkp file. For example, to exclude bands 2, 6, 7, 8 and 12:

exclude_bands : 2, 6-8, 12

`integer :: select_projections(:)`¶

A list of projections to be included in the wannierisation procedure. In the case that num_proj is greater than num_wann, this keyword allows a subset of the projections in the projection matrices to be used. For example, to select the projections given by the indices 2, 6, 7, 8 and 12:

select_projections : 2, 6-8, 12

`logical :: auto_projections`¶

If .true. and no projections block is defined, then wannier90 writes an additional block in the .nnkp file during the pre-processing step, to instruct the interface code to automatically generate the \(A_{mn}^{(\mathbf{k})}\).

For additional information on the behavior and on the added block, see Sec. [sec:auto-projections-block]{reference-type="ref" reference="sec:auto-projections-block"}.

Note: the interface code (e.g. pw2wannier90.x) must have at least one implementation of a method to automatically generate initial projections in order for this option to be usable.

The default value of this parameter is \(\verb#false#\).

`character(len=20) :: restart`¶

If restart is present the code will attempt to restart the calculation from the seedname.chk file. The value of the parameter determines the position of the restart

The valid options for this parameter are:

default. Restart from the point at which the check file seedname.chk was written
wannierise. Restart from the beginning of the wannierise routine
plot. Go directly to the plotting phase
transport. Go directly to the transport routines

`character(len=20) :: wvfn_formatted`¶

If wvfn_formatted=true, then the wavefunctions will be read from disk as formatted (ie ASCII) files; otherwise they will be read as unformatted files. Unformatted is generally preferable as the files will take less disk space and I/O is significantly faster. However such files will not be transferable between all machine architectures and formatted files should be used if transferability is required (i.e., for test cases).

The default value of this parameter is \(\verb#false#\).

`character(len=20) :: spin`¶

For bands from a spin polarised calculation spin determines which set of bands to read in, either up or down.

The default value of this parameter is up.

`integer :: timing_level`¶

Determines the amount of timing information regarding the calculation that will be written to the output file. A value of 1 produces the least information.

The default value is 1.

`logical :: translate_home_cell`¶

Determines whether to translate the final Wannier centres to the home unit cell at the end of the calculation. Mainly useful for molecular systems in which the molecule resides entirely within the home unit cell and user wants to write an xyz file (write_xyz=.true.) for the WF centres to compare with the structure.

The default value is false.

`logical :: write_xyz`¶

Determines whether to write the atomic positions and final Wannier centres to an xyz file, seedname_centres.xyz, for subsequent visualisation.

The default value is false.

`logical :: write_vdw_data`¶

Determines whether to write seedname.vdw for subsequent post-processing by the w90vdw utility (in the utility/w90vdw/ directory of the distribution) for calculating van der Waals energies. Brillouin zone sampling must be at the Gamma-point only.

The default value is false.

Disentanglement¶

These keywords control the disentanglement routine of Ref. ³, i.e., the iterative minimisation of \(\Omega_{\mathrm{I}}\). This routine will be activated if num_wann\(\:<\:\)num_bands.

`real(kind=dp) :: dis_win_min`¶

The lower bound of the outer energy window for the disentanglement procedure. Units are eV.

The default is the lowest eigenvalue in the system.

`real(kind=dp) :: dis_win_max`¶

The upper bound of the outer energy window for the disentanglement procedure. Units are eV.

The default is the highest eigenvalue in the given states (i.e., all states are included in the disentanglement procedure).

`real(kind=dp) :: dis_froz_min`¶

The lower bound of the inner energy window for the disentanglement procedure. Units are eV.

If dis_froz_max is given, then the default for dis_froz_min is dis_win_min.

`real(kind=dp) :: dis_froz_max`¶

The upper bound of the inner (frozen) energy window for the disentanglement procedure. If dis_froz_max is not specified, then there are no frozen states. Units are eV.

No default.

`logical :: dis_froz_proj`¶

To activate projectability disentanglement procedure, which selectively discard/disentangle/freeze state \(\vert n \mathbf{k}\rangle\) based on its projectability onto some localized atomic orbitals.

Note: this requires the amn file is properly normalized, i.e., projectability computed from \(A A^\dagger\) must be smaller than or equal to 1. The pseudo-atomic projection satisfies such requirement, see 3.6.

Additionally, one can combine projectability disentanglement with energy disentanglement, i.e., enable both dis_proj_min/max and dis_froz_min/max simultaneously in the win file. These settings will freeze the union of inner energy window and high-projectability states, and exclude the union of states outside outer energy window and having low projectability.

`real(kind=dp) :: dis_proj_min`¶

The lower bound for the projectability disentanglement procedure.

For states with projectabilities smaller than dis_proj_min, they will be discarded in the disentanglement procedure, i.e., similar to the case of outside of the outer energy window.

For states with projectabilities larger than or equal to dis_proj_min, they will be included in the disentanglement procedure, i.e., similar to the case of inside the outer energy window.

No unit.

The default value is 0.95.

`real(kind=dp) :: dis_proj_max`¶

The upper bound for the projectability disentanglement procedure. For states with projectability larger than or equal to dis_proj_max, they will be freezed in the disentanglement procedure, i.e., similar to the case of inside the inner energy window.

No unit.

The default value is 0.01.

`integer :: dis_num_iter`¶

In the disentanglement procedure, the number of iterations used to extract the most connected subspace.

The default value is 200.

`real(kind=dp) :: dis_mix_ratio`¶

In the disentanglement procedure, the mixing parameter to use for convergence (see pages 4-5 of Ref. ³). A value of 0.5 is a 'safe' choice. Using 1.0 (i.e., no mixing) often gives faster convergence, but may cause the minimisation of \(\Omega_{\mathrm{I}}\) to be unstable in some cases.

Restriction: \(0.0<\:\)dis_mix_ratio\(\:\leq 1.0\)

The default value is 0.5

`real(kind=dp) :: dis_conv_tol`¶

In the disentanglement procedure, the minimisation of \(\Omega_{\mathrm{I}}\) is said to be converged if the fractional change in the gauge-invariant spread between successive iterations is less than dis_conv_tol for dis_conv_window iterations. Units are Å\(^2\).

The default value is 1.0E-10

`integer :: dis_conv_window`¶

In the disentanglement procedure, the minimisation is said to be converged if the fractional change in the spread between successive iterations is less than dis_conv_tol for dis_conv_window iterations.

The default value of this parameter is 3.

`integer :: dis_spheres_num`¶

Number of spheres in reciprocal space where the k-dependent disentanglement is performed. No disentanglement is performed for those k-points that are not included in any of the spheres.

The default is 0, which means disentangle at every k-point in the full BZ (the standard mode in Wannier90).

`integer :: dis_spheres_first_wann`¶

Index of the first band that has to be considered as a Wannier function. Used only if dis_spheres_num is greater than zero. At k-points where disentanglement is not performed the bands from dis_spheres_first_wann to dis_spheres_first_wann+num_wann are used to wannierise. The bands excluded using exclude_bands should not be counted.

The default is 1, the band at the lowest energy.

dis_spheres¶

Each line gives the coordinate \(\mathbf{K}=K_1 \mathbf{B}_{1} + K_2 \mathbf{B}_{2} + K_3 \mathbf{B}_3\) of a k-point representing the center of one of the spheres used for k-dependent disentanglement. The same crystallographic units as for kpoints are used here. Each k-point coordinate \(\mathbf{K}^i\) must the followed by the respectice sphere radius \(r_{i}\) in inverse angstrom (on the same line).

The number of lines must be equal to dis_spheres_num.

begin dis_spheres \(\(\begin{array}{cccc} K^{1}_{1} & K^{1}_{2} & K^{1}_{3} & r_{1} \\ K^{2}_{1} & K^{2}_{2} & K^{2}_{3} & r_{2} \\ \vdots \end{array}\)\) end dis_spheres

There is no default.

Wannierise¶

Iterative minimisation of \(\widetilde{\Omega}\), the non-gauge-invariant part of the spread functional.

`integer :: num_iter`¶

Total number of iterations in the minimisation procedure. Set num_iter=0 if you wish to generate projected WFs rather than maximally-localized WFs (see Example 8 in the Tutorial).

The default value is 100

`integer :: num_cg_steps`¶

Number of conjugate gradient steps to take before resetting to steepest descents.

The default value is 5

`integer :: conv_window`¶

If conv_window\(\:>1\), then the minimisation is said to be converged if the change in \(\Omega\) over conv_window successive iterations is less than conv_tol. Otherwise, the minimisation proceeds for num_iter iterations (default).

The default value is -1

`real(kind=dp) :: conv_tol`¶

If conv_window\(\:>1\), then this is the convergence tolerance on \(\Omega\), otherwise not used. Units are Å\(^2\).

The default value is 1.0E-10

`logical :: precond`¶

Whether or not to use preconditioning to speed up the minimization of the spreads. This is based on the same idea as the classical Tetter-Payne-Allan preconditionning for DFT and dampens the high-frequency oscillations of the gradient due to contributions from large real lattice vectors. It is useful when the optimization is slow, especially on fine grids. When optimisation<3, this uses a slower algorithm to save memory.

The default value is false.

`real(kind=dp) :: conv_noise_amp`¶

If conv_noise_amp\(\:>0\), once convergence (as defined above) is achieved, some random noise \(f\) is added to the search direction, and the minimisation is continued until convergence is achieved once more. If the same value of \(\Omega\) as before is arrived at, then the calculation is considered to be converged. If not, then random noise is added again and the procedure repeated up to a maximum of conv_noise_num times. conv_noise_amp is the amplitude of the random noise \(f\) that is added to the search direction: \(0 < |f| <\:\)conv_noise_amp. This functionality requires conv_window\(\:>1\). If conv_window is not specified, it is set to the value 5 by default.

If conv_noise_amp\(\:\leq 0\), then no noise is added (default).

The default value is -1.0

`integer :: conv_noise_num`¶

If conv_noise_amp\(\:>0\), then this is the number of times in the minimisation that random noise is added.

The default value is 3

`integer :: num_dump_cycles`¶

Write sufficient information to do a restart every num_dump_cycles iterations.

The default is 100

`integer :: num_print_cycles`¶

Write data to the master output file seedname.wout every num_print_cycles iterations.

The default is 1

`logical :: write_r2mn`¶

If \(\verb#write_r2mn#=\verb#true#\), then the matrix elements \(\langle m|r^2|n\rangle\) (where \(m\) and \(n\) refer to WF) are written to file seedname.r2mn at the end of the Wannierisation procedure.

The default value of this parameter is false.

`logical :: guiding_centres`¶

Use guiding centres during the minimisation, in order to avoid local minima.

wannier90 uses a logarithm definition of the spread functional. As we are taking the log of a complex argument there is a possibility that the algorithm might make inconsistent choices for the branch cut. This manifests itself as complex WF with a large spread. By using guiding centres the code will attempt to make a consistent choice of branch cut. Experience shows that with guiding_centres set to true this problem is avoided and doing so does not cause any problems. For this reason we recommend setting guiding_centres to true where possible (it is only not possible if an explicit projection block is not defined).

The default value is false.

`integer :: num_guide_cycles`¶

If guiding_centres is set to true, then the guiding centres are used only every num_guide_cycles.

The default value is 1.

`integer :: num_no_guide_iter`¶

If guiding_centres is set to true, then the guiding centres are used only after num_no_guide_iter minimisation iterations have been completed.

The default value is 0.

`real(kind=dp) :: trial_step`¶

The value of the trial step for the parabolic fit in the line search minimisation used in the minimisation of the spread function. Cannot be used in conjunction with fixed_step (see below). If the minimisation procedure doesn't converge, try decreasing the value of trial_step to give a more accurate line search.

The default value is 2.0

`real(kind=dp) :: fixed_step`¶

If this is given a value in the input file, then a fixed step of length fixed_step (instead of a parabolic line search) is used at each iteration of the spread function minimisation. Cannot be used in conjunction with trial_step. This can be useful in cases in which minimisation with a line search fails to converge.

There is no default value.

`logical :: use_bloch_phases`¶

Determines whether to use the Bloch functions as the initial guess for the projections. Can only be used if disentanglement = false.

The default value is false.

`logical :: site_symmetry`¶

Construct symmetry-adapted Wannier functions. For the detail of the theoretical background, see Ref. ⁴. Cannot be used in conjunction with the inner (frozen) energy window.

The default value is false.

`real(kind=dp) :: symmetrize_eps`¶

Convergence threshold to check whether the symmetry condition (Eq. (19) in Ref. ⁴) on the unitary matrix \(\mathbf{U}^{(\mathbf{k})}\) is satisfied or not. See also Eq. (29) in Ref. ⁴. Used when site_symmetry = .true.

The default value is 1.0E-3.

`integer :: slwf_num`¶

The number of objective Wannier functions for selective localisation in the selectively localised Wannier function (SLWF) method of Ref. ⁵. These functions are obtained by minimising the spread functional only with respect to the degrees of freedom of a subset of slwf_num \(<\) num_wann functions. At convergence, the objective WFs will have a minimum cumulative spread, whereas the remaining num_wann \(-\) slwf_num functions are left unoptimised. The initial guesses for the objective WFs are given by the first slwf_num orbitals in the projections block. If slwf_num = num_wann no selective minimisation is performed. In this case, wannier90 will simply generate a set of num_wann MLWFs.

The default is num_wann.

`logical :: slwf_constrain`¶

If slwf_constrain=true, then the centres of the objective Wannier functions are constrained to either the centres of the first slwf_num orbitals in the projections block or to new positions specified in the slwf_centres block (see Sec. 2.8.22{reference-type="ref" reference="sec:centre_constraints"}). In this case, a modified spread functional, \(\Omega_c\), with the addition of a constraint term, as described in Ref. ⁵.

The default is false

`real(kind=dp) :: slwf_lambda`¶

The value of the Lagrange multiplier \(\lambda\) for the constraint term in term added to modify the spread functional: \(\lambda \sum_{n=1}^{J'} \left(\overline{\mathbf{r}}_n - \mathbf{r}_{0n}\right)^2\), where \(J'\) is slwf_num, and \(\overline{\mathbf{r}}_{n}\) and \(\mathbf{r}_{0n}\) are the centre and target centre, respectively, for the \(n^{\text{th}}\) objective WF.

The default is 0.0.

Constraints on centres¶

If slwf_constrain=true, then by default the centres to which the slwf_num objective Wannier function centres are constrained are given by the first slwf_num rows of the projections block.

Optionally, the slwf_centres block may be used to define alternative target centres for some or all of the slwf_num objective Wannier functions.

The block below shows an example of how to set the constraints:

begin slwf_centres\ 2 0.0 0.0 0.0\ 4 0.25 0.0 0.0\ end slwf_centres

The first line sets the constraint for the centre of objective WF number 2 (as defined by the order of WFs in the projections block) to (0.0,0.0,0.0) in fractional co-ordinates.
The second line sets the constraint for the centre of objective WF number 4 (as defined by the order of WFs in the projections block) to (0.25,0.0,0.0) in fractional co-ordinates.
The target centres of all other objective Wannier functions remain as the centres given in the corresponding rows of the projections block.

Post-Processing¶

Capabilities:

Plot the WF
Plot the interpolated band structure
Plot the Fermi surface
Output the Hamiltonian in the WF basis
Transport calculation (quantum conductance and density of states)

`logical :: wannier_plot`¶

If \(\verb#wannier_plot#=\verb#true#\), then the code will write out the Wannier functions in a format specified by wannier_plot_format

The default value of this parameter is false.

`integer :: wannier_plot_list(:)`¶

A list of WF to plot. The WF numbered as per the seedname.wout file after the minimisation of the spread.

The default behaviour is to plot all WF. For example, to plot WF 4, 5, 6 and 10:

wannier_plot_list : 4-6, 10

`integer :: wannier_plot_supercell`¶

The code generates the WFs on a grid corresponding to a 'super-unit-cell'. If wannier_plot_supercell is provided as a single integer, then the size of the super-unit-cell is wannier_plot_supercell times the size of the unit cell along all three linear dimensions (the 'home' unit cell is kept approximately in the middle); otherwise, if three integers are provided, the size of the super-unit-cell is wannier_plot_supercell(i) times the size of the unit cell along the \(i-\)th linear dimension.

The default value is 2.

`character(len=20) :: wannier_plot_format`¶

WF can be plotted in either XCrySDen (xsf) format or Gaussian cube format. The valid options for this parameter are:

xcrysden (default)
cube

If wannier_plot_format=xsf: the code outputs the WF on the entire super-unit-cell specified by wannier_plot_supercell.

If wannier_plot_format=cube: the code outputs the WF on a grid that is smaller than the super-unit-cell specified by wannier_plot_supercell. This grid is determined by wannier_plot_mode, wannier_plot_radius and wannier_plot_scale, described in detail below.

The code is able to output Gaussian cube files for systems with non-orthogonal lattice vectors. Many visualisation programs (including XCrySDen), however, are only able to handle cube files for systems with orthogonal lattice vectors. One visualisation program that is capable of dealing with non-orthogonal lattice vectors is VESTA (http://jp-minerals.org/vesta/en/).

Note

It's worth noting that another visualisation program, VMD (http://www.ks.uiuc.edu/Research/vmd), is able to deal with certain special cases of non-orthogonal lattice vectors; see http://www.ks.uiuc.edu/Research/vmd/plugins/molfile/cubeplugin.html for details.

`character(len=20) :: wannier_plot_mode`¶

Choose the mode in which to plot the WF, either as a molecule or as a crystal.

The valid options for this parameter are:

crystal (default)
molecule

If wannier_plot_format=cube:

if wannier_plot_mode = molecule, then wherever the WF centre sits in the supercell, the origin of the cube is shifted (for the purpose of plotting only, ie, nothing is done to the U matrices etc) to coincide with the centre of mass of the atomic positions specified by the user in the .win input file. These atomic positions are also written to the cube file, so when it is visualised, the WF appears superimposed on the molecular structure.
if wannier_plot_mode = crystal, then the WF is not shifted, but instead the code searches for atoms that are within a radius of wannier_plot_scale \(\times\) wannier_plot_radius of the WF centre and writes the coordinates of these atoms to the cube file. In this way, when the cube file is visualised, the WF appears superimposed on the nearest atoms to the WF centre.
crystal mode can be used for molecules, and molecule mode can be used for crystals.

`real(kind=dp) :: wannier_plot_radius`¶

If wannier_plot_format=cube, then wannier_plot_radius is the radius of the sphere that must fit inside the parallelepiped in which the WF is plotted. wannier_plot_radius must be greater than 0. Units are Å.

The default value is 3.5.

`real(kind=dp) :: wannier_plot_scale`¶

If wannier_plot_format=cube and wannier_plot_mode=crystal, then the code searches for atoms that are within a radius of wannier_plot_scale \(\times\) wannier_plot_radius of the WF centre and writes the coordinates of these atoms to the cube file. In this way, when the cube file is visualised, the WF appears superimposed on the nearest atoms to the WF centre. wannier_plot_scale must be greater than 0. This parameter is dimensionless.

The default value is 1.0.

`character(len=20) :: wannier_plot_spinor_mode`¶

If \(\verb#spinors#=\verb#true#\) then this parameter controls the quantity to plot. For a spinor WF with components \([\phi,\psi]\) the quatity plotted is

total (default). \(\sqrt{[|\phi|^2+|\psi|^2}\)
up. \(|\phi|\times sign(Re\{\phi\})\) if \(\verb#wannier_plot_spinor_phase#=\verb#true#\), otherwise \(|\phi|\)
down. \(|\psi|\times sign(Re\{\psi\})\) if \(\verb#wannier_plot_spinor_phase#=\verb#true#\), otherwise \(|\psi|\)

Note: making a visual representation of a spinor WF is not as straightforward as for a scalar WF. While a scalar WF is typically a real valued function, a spinor WF is a complex, two component spinor. wannier90 is able to plot several different quantities derived from a spinor WF which should give you a good idea of the nature of the WF.

`logical :: wannier_plot_spinor_phase`¶

If \(\verb#wannier_plot_spinor_phase#=\verb#true#\) phase information will be taken into account when plotting a spinor WF.

`logical :: bands_plot`¶

If \(\verb#bands_plot#=\verb#true#\), then the code will calculate the band structure, through Wannier interpolation, along the path in k-space defined by bands_kpath using bands_num_points along the first section of the path and write out an output file in a format specified by bands_plot_format.

The default value is false.

kpoint_path¶

Defines the path in k-space along which to calculate the bandstructure. Each line gives the start and end point (with labels) for a section of the path. Values are in fractional coordinates with respect to the primitive reciprocal lattice vectors.

begin kpoint_path \(\(\begin{array}{cccccccc} G & 0.0 & 0.0 & 0.0 & L & 0.0 & 0.0 & 1.0 \\ L & 0.0 & 0.0 & 1.0 & N & 0.0 & 1.0 & 1.0 \\ \vdots \end{array}\)\) end kpoint_path

There is no default

`integer :: bands_num_points`¶

If \(\verb#bands_plot#=\verb#true#\), then the number of points along the first section of the bandstructure plot given by kpoint_path. Other sections will have the same density of k-points.

The default value for bands_num_points is 100.

`character(len=20) :: bands_plot_format`¶

Format in which to plot the interpolated band structure. The valid options for this parameter are:

gnuplot (default)
xmgrace

Note: it is possible to request output in both formats eg \(\verb#bands_format#=\verb#gnuplot xmgrace#\)

`integer :: bands_plot_project(:)`¶

If present wannier90 will compute the contribution of this set of WF to the states at each point of the interpolated band structure. The WF are numbered according to the seedname.wout file. The result is written in the seedname_band.dat file, and a corresponding gnuplot script to seedname_band_proj.dat .

For example, to project on to WFs 2, 6, 7, 8 and 12:

bands_plot_project : 2, 6-8, 12

`character(len=20) :: bands_plot_mode`¶

To interpolate the band structure along the k-point path, either use the Slater-Koster interpolation scheme or truncate the Hamiltonian matrix in the WF basis. Truncation criteria are provided by hr_cutoff and dist_cutoff.

The valid options for this parameter are:

s-k (default)
cut

`integer :: bands_plot_dim`¶

Dimension of the system. If \(\verb#bands_plot_dim#<\:\)3 and \(\verb#bands_plot_mode#=\verb#cut#\), lattice vector \(\mathbf{R}=N_1 \mathbf{A}_{1} + N_2 \mathbf{A}_{2} + N_3 \mathbf{A}_3\), where \(N_i=0\) if \(\mathbf{A}_i\) is parallel to any of the confined directions specified by one_dim_axis, are exclusively used in the band structure interpolation.

The valid options for this parameter are:

3 (default)
2
1

`logical :: fermi_surface_plot`¶

If \(\verb#fermi_surface_plot#=\verb#true#\), then the code will calculate, through Wannier interpolation, the eigenvalues on a regular grid with fermi_surface_num_points in each direction. The code will write a file in bxsf format which can be read by XCrySDen in order to plot the Fermi surface.

The default value is false.

`integer :: fermi_surface_num_points`¶

If \(\verb#fermi_surface_plot#=\verb#true#\), then the number of divisions in the regular k-point grid used to calculate the Fermi surface.

The default value for fermi_surface_num_points is 50.

`real(kind=dp) :: fermi_energy`¶

The Fermi energy in eV. This parameter is written into the bxsf file. If fermi_energy is specified, fermi_energy_min, fermi_energy_max, and fermi_energy_step should not be specified, and vice-versa.

The default value is 0.0

`real(kind=dp) :: fermi_energy_min`¶

Instead of specifyfing a single Fermi energy, it is possible to scan the Fermi level over a range of values, and recompute certain quantities for each \(\varepsilon_F\). This is the minimum value in the range (in eV).

Note

Scanning the Fermi level is currently supported only by the postw90 module berry, for berry_task=ahc,morb. For all other functionalities that require a knowledge of \(\varepsilon_F\), use fermi_energy instead.

There is no default value.

`real(kind=dp) :: fermi_energy_max`¶

The maximum value in the range of Fermi energies. Units are eV.

The default value is fermi_energy_min+1.0.

`real(kind=dp) :: fermi_energy_step`¶

Difference between consecutive values of the Fermi energy when scanning from fermi_energy_min to fermi_energy_max. Units are eV.

The default value is 0.01.

`character(len=20) :: fermi_surface_plot_format`¶

Format in which to plot the Fermi surface. The valid options for this parameter are:

xcrysden (default)

`logical :: write_hr`¶

If \(\verb#write_hr#=\verb#true#\), then the Hamiltonian matrix in the WF basis will be written to a file seedname_hr.dat.

The default value is false.

`logical :: write_rmn`¶

If \(\verb#write_rmn#=\verb#true#\), then the position operator in the WF basis will be written to a file seedname_r.dat.

The default value is false.

`logical :: write_bvec`¶

If \(\verb#write_bvec#=\verb#true#\), then the the matrix elements of bvector and their weights will be written to a file seedname.bvec.

The default value is false.

`logical :: write_tb`¶

If \(\verb#write_tb#=\verb#true#\), then the lattice vectors, together with the Hamiltonian and position-operator matrices in the WF basis, will be written to a file seedname_tb.dat, in units of Angstrom and eV.

The default value is false.

`logical :: transport`¶

If \(\verb#transport#=\verb#true#\), then the code will calculate quantum conductance and density of states of a one-dimensional system. The results will be written to files seedname_qc.dat and seedname_dos.dat, respectively. Since both quantities are a function of energy, they will be evaluated from tran_win_min to tran_win_max with an interval of tran_energy_step.

The default value of this parameter is false.

`character(len=20) :: transport_mode`¶

If \(\verb#transport_mode#=\verb#bulk#\), quantum conductance and density of states are calculated for a perfectly-periodic one-dimensional system. In this case, the transport part can either use the Hamiltonian matrix in the WF basis generated by wannier90 or a Hamiltonian matrix provided by the external file seedname_htB.dat.

If \(\verb#transport_mode#=\verb#lcr#\), quantum conductance and density of states are calculated for a system where semi-infinite, left and right leads are connected through a central conductor region. In this case, the transport part will work independently from the disentanglement and wannierise procedure. Details of the method is described in Ref. ⁶.

If \(\verb#tran_read_ht# = \verb#true#\) then the Hamiltonian matrices must be provided by the five external files: seedname_htL.dat, seedname_htLC.dat, seedname_htC.dat, seedname_htCR.dat, seedname_htR.dat. If \(\verb#tran_read_ht# = \verb#false#\) then the Hamiltonian matrices are found automatically provided the supercell adheres to conditions outlined in Section 7.3{reference-type="ref" reference="sec:2c2"}.

The valid options for this parameter are:

bulk (default)
lcr

`real(kind=dp) :: tran_win_min`¶

The lower bound of the energy window for the transport calculation. Units are eV.

The default value is -3.0.

`real(kind=dp) :: tran_win_max`¶

The upper bound of the energy window for the transport calculation. Units are eV.

The default value is 3.0.

`real(kind=dp) :: tran_energy_step`¶

Sampling interval of the energy values from tran_win_min to tran_win_max. Units are eV.

The default value is 0.01.

`real(kind=dp) :: fermi_energy`¶

The Fermi energy in eV. The energy axis of the quantum conductance and density of states data will be shifted rigidly by this amount.

The default value is 0.0

`integer :: tran_num_bb`¶

Size of a bulk Hamiltonian matrix. This number is equal to the number of WFs in one principal layer.

A one-dimensional system can be viewed as an array of principal layers which are defined in a way that localized basis functions inside a certain principal layer only interact with those in the nearest neighbor principal layer. In wannier90 a principal layer will be an integer multiple of a unit cell, and the size is determined by hr_cutoff and/or dist_cutoff. The criterion is rather arbitrary when WFs are adopted as a localized basis set, and it is up to a user's choice.

The default value is 0.

`integer :: tran_num_ll`¶

Size of a left-lead Hamiltonian matrix. If \(\verb#transport_mode# = \verb#lcr#\) and \(\verb#tran_read_ht# = \verb#false#\) then tran_num_ll is the number of Wannier functions in a principal layer.

The default value is 0.

`integer :: tran_num_rr`¶

Size of a right-lead Hamiltonian matrix.

The default value is 0.

`integer :: tran_num_cc`¶

Size of a conductor Hamiltonian matrix.

The default value is 0.

`integer :: tran_num_lc`¶

Number of columns in a left-lead_conductor Hamiltonian matrix. Number of rows must be equal to tran_num_ll.

The default value is 0.

`integer :: tran_num_cr`¶

Number of rows in a conductor_right-lead Hamiltonian matrix. Number of columns must be equal to tran_num_rr.

The default value is 0.

`integer :: tran_num_cell_ll`¶

Number of unit cells in one principal layer of left lead. Used if \(\verb#transport_mode# = \verb#lcr#\) and \(\verb#tran_read_ht# = \verb#false#\).

The default value is 0.

`integer :: tran_num_cell_rr`¶

Number of unit cells in one principal layer of right lead. Not used at present.

The default value is 0.

`integer :: tran_num_bandc`¶

Half-bandwidth+1 of a band-diagonal conductor Hamiltonian matrix.

The Hamiltonian matrix of a central conductor part, which is read from seedname_htC.dat, will be diagonally dominant when tran_num_cc is very large. tran_num_bandc is used to construct a compact matrix which contains the non-zero band-diagonal part of a full conductor Hamiltonian matrix. Setting this parameter is only meaningful when tran_num_bandc is greater than tran_num_lc and tran_num_cr.

The default value is 0.

`logical :: tran_write_ht`¶

If \(\verb#tran_write_ht#=\verb#true#\), then the Hamiltonian matrix formatted for the transport calculation will be written to a file seedname_htB.dat.

The default value is false.

`logical :: tran_read_ht`¶

If \(\verb#tran_write_ht#=\verb#true#\), then the Hamiltonian matrix formatted for the transport calculation will be read from a set of files described in the parameter transport_mode. Set \(\verb#tran_write_ht#=\verb#false#\) to perform automated lcr calculations (see Section 7.3{reference-type="ref" reference="sec:2c2"}).

The default value is false.

`logical :: tran_use_same_lead`¶

If \(\verb#tran_use_same_lead#=\verb#true#\), then the left and the right leads are the same. In this case, seedname_htR.dat is not required.

The default value is true.

`real(kind=dp) :: tran_group_threshold`¶

Used to group and sort Wannier functions according to the positions of their centres. Wannier functions in a group are within tran_group_threshold from one another in x,y and z directions. Units are Å

The default is 0.15

`real(kind=dp) :: translation_centre_frac(3)`¶

Centre of the unit cell to which the final Wannier centres are translated. Numbers are in fractional coordinates with respect to the lattice vectors.

The default value is (0.0,0.0,0.0).

`logical :: use_ws_distance`¶

Improves the interpolation of the k-space Hamiltonian, by applying a translation to each WF by a basis vector of the super-lattice that minimises the distance between their centres. The translation is dependent on both WF and on the unit cell vector to which they belong, i.e., translate function \(W_j({\bf r}-{\bf R})\) inside the Wigner-Seitz cell centred on WF \(W_i({\bf r})\).

For a longer explanation, see Chapter [chap:interpolation]{reference-type="ref" reference="chap:interpolation"}.

If false the code puts all the WF in the home cell, only possible choice until wannier90 v2.0.1.

The default value is true (default changed since v.3.0). Introduced in v2.1.

`real(kind=dp) :: ws_distance_tol`¶

Tolerance when determining whether two values \(\|\mathbf{d}_{ij\mathbf{R}} + \tilde{\mathbf{R}}_{nml} \|\) and \(\|\mathbf{d}_{ij\mathbf{R}} + \tilde{\mathbf{R}}_{n'm'l'} \|\) (as defined in chapter [chap:interpolation]{reference-type="ref" reference="chap:interpolation"}) for the shortest distance between two Wannier functions are equivalent. If the difference in distance (in Angstrom) is less than ws_distance_tol, they are taken to be equivalent.

The default value is \(10^{-5}\).

`:: ws_search_size`¶

Maximum absolute value for the integers \(n,m,l\) that identify the super-lattice vectors \(\tilde{\mathbf{R}}_{nml}\) (see chapter [chap:interpolation]{reference-type="ref" reference="chap:interpolation"}) when searching for points inside the Wigner-Seitz cell. If ws_search_size is provided as a single integer, then the number of repetitions of the Born-von Karman cell is the same along all three linear dimensions; otherwise, if three integers are provided, the number of repetitions along the \(i-\)th linear dimension is ws_search_size(i). The variable is used both in hamiltonian.F90 and in ws_distance.F90. In the latter case, its value is incremented by one in order to account for WFs whose centre wanders away from the original reference unit cell.\ The default value is generally sufficient, but might need to be increased in case of elongated cells.

The default value is 2.

`logical :: write_u_matrices`¶

Write the \(\mathbf{U}^{(\mathbf{k})}\) and \(\mathbf{U}^{\mathrm{dis}(\mathbf{k})}\) matrices obtained at the end of wannierization to files seedname_u.mat and seedname_u_dis.mat, respectively.

The default value is false.

`real(kind=dp) :: hr_cutoff`¶

The absolute value of the smallest matrix element of the Hamiltonian in the WF basis. If \(h_{mn}(\mathbf{R})>\:\)hr_cutoff, then the matrix element \(h_{mn}(\mathbf{R})\) is retained and used in the band structure interpolation (when \(\verb#bands_plot_mode#=\verb#cut#\)) or in the transport calculation. Otherwise it is deemed to be insignificant and is discarded. Units are eV.

The default value is 0.0.

`real(kind=dp) :: dist_cutoff`¶

The largest distance between two WFs for which the Hamiltonian matrix element is retained and used in the band interpolation (when \(\verb#bands_plot_mode#=\verb#cut#\)) or in the transport calculation. Units are Å.

The default value is 1000.0.

`character(len=20) :: dist_cutoff_mode`¶

Dimension in which the distance between two WFs is calculated. The vector connecting two WFs may be projected to a line (one_dim) or a plane (two_dim). The size of the projected vector is calculated, and dist_cutoff is applied. When one_dim or two_dim is used, one_dim_axis must be given to specify extended or confined direction.

The valid options for this parameter are:

three_dim (default)
two_dim
one_dim

`character(len=20) :: one_dim_axis`¶

Extended direction for a one-dimensional system or confined direction for a two-dimensional system. This direction must be parallel to one of the Cartesian axes.

The valid options for this parameter are:

x
y
z

No default.

N. Marzari and D. Vanderbilt. Maximally localized generalized wannier functions for composite energy bands. Phys. Rev. B, 56:12847, 1997. ↩↩
F. Gygi, J. L. Fattebert, and E. Schwegler. Computation of maximally localized wannier functions using a simultaneous diagonalization algorithm. Comput. Phys. Commun., 155:1–6, 2003. ↩
I. Souza, N. Marzari, and D. Vanderbilt. Maximally localized wannier functions for entangled energy bands. Phys. Rev. B, 65:035109, 2001. ↩↩
R. Sakuma. Symmetry-adapted wannier functions in the maximal localization procedure. Phys. Rev. B, 87:235109, 2013. ↩↩↩
Runzhi Wang, Emanuel A. Lazar, Hyowon Park, Andrew J. Millis, and Chris A. Marianetti. Selectively localized wannier functions. Physical Review B, 10 2014. doi:10.1103/PhysRevB.90.165125. ↩↩
Marco Buongiorno Nardelli. Electronic transport in extended systems: application to carbon nanotubes. Phys. Rev. B, 60:7828, 1999. ↩

Parameters¶

Usage¶

seedname.win File¶

Keyword List¶

System¶

integer :: num_wann¶

integer :: num_bands¶

Cell Lattice Vectors¶

Ionic Positions¶

Cartesian coordinates¶

Fractional coordinates¶

integer, dimension :: mp_grid(3)¶

K-points¶

logical :: gamma_only¶

logical :: spinors¶

Shells¶

integer :: shell_list(:)¶

integer :: search_shells¶

logical :: skip_B1_tests¶

integer, dimension(:, 5) :: nnkpts¶

real(kind=dp) :: kmesh_tol¶

Projection¶

Job Control¶

logical :: postproc_setup¶

integer :: iprint¶

integer :: optimisation¶

character(len=20) :: length_unit¶

character(len=50) :: devel_flag¶

integer :: exclude_bands(:)¶

integer :: select_projections(:)¶

logical :: auto_projections¶

character(len=20) :: restart¶

character(len=20) :: wvfn_formatted¶

character(len=20) :: spin¶

integer :: timing_level¶

logical :: translate_home_cell¶

logical :: write_xyz¶

logical :: write_vdw_data¶

Disentanglement¶

real(kind=dp) :: dis_win_min¶

real(kind=dp) :: dis_win_max¶

real(kind=dp) :: dis_froz_min¶

real(kind=dp) :: dis_froz_max¶

logical :: dis_froz_proj¶

real(kind=dp) :: dis_proj_min¶

real(kind=dp) :: dis_proj_max¶

integer :: dis_num_iter¶

real(kind=dp) :: dis_mix_ratio¶

real(kind=dp) :: dis_conv_tol¶

integer :: dis_conv_window¶

integer :: dis_spheres_num¶

integer :: dis_spheres_first_wann¶

dis_spheres¶

Wannierise¶

integer :: num_iter¶

integer :: num_cg_steps¶

integer :: conv_window¶

real(kind=dp) :: conv_tol¶

logical :: precond¶

real(kind=dp) :: conv_noise_amp¶

integer :: conv_noise_num¶

integer :: num_dump_cycles¶

integer :: num_print_cycles¶

logical :: write_r2mn¶

logical :: guiding_centres¶

integer :: num_guide_cycles¶

integer :: num_no_guide_iter¶

real(kind=dp) :: trial_step¶

real(kind=dp) :: fixed_step¶

logical :: use_bloch_phases¶

logical :: site_symmetry¶

real(kind=dp) :: symmetrize_eps¶

integer :: slwf_num¶

logical :: slwf_constrain¶

real(kind=dp) :: slwf_lambda¶

Constraints on centres¶

Post-Processing¶

logical :: wannier_plot¶

integer :: wannier_plot_list(:)¶

integer :: wannier_plot_supercell¶

`seedname.win` File¶

`integer :: num_wann`¶

`integer :: num_bands`¶

`integer, dimension :: mp_grid(3)`¶

`logical :: gamma_only`¶

`logical :: spinors`¶

`integer :: shell_list(:)`¶

`integer :: search_shells`¶

`logical :: skip_B1_tests`¶

`integer, dimension(:, 5) :: nnkpts`¶

`real(kind=dp) :: kmesh_tol`¶

`logical :: postproc_setup`¶

`integer :: iprint`¶

`integer :: optimisation`¶

`character(len=20) :: length_unit`¶

`character(len=50) :: devel_flag`¶

`integer :: exclude_bands(:)`¶

`integer :: select_projections(:)`¶

`logical :: auto_projections`¶

`character(len=20) :: restart`¶

`character(len=20) :: wvfn_formatted`¶

`character(len=20) :: spin`¶

`integer :: timing_level`¶

`logical :: translate_home_cell`¶

`logical :: write_xyz`¶

`logical :: write_vdw_data`¶

`real(kind=dp) :: dis_win_min`¶

`real(kind=dp) :: dis_win_max`¶

`real(kind=dp) :: dis_froz_min`¶

`real(kind=dp) :: dis_froz_max`¶

`logical :: dis_froz_proj`¶

`real(kind=dp) :: dis_proj_min`¶

`real(kind=dp) :: dis_proj_max`¶

`integer :: dis_num_iter`¶

`real(kind=dp) :: dis_mix_ratio`¶

`real(kind=dp) :: dis_conv_tol`¶

`integer :: dis_conv_window`¶

`integer :: dis_spheres_num`¶

`integer :: dis_spheres_first_wann`¶

`integer :: num_iter`¶

`integer :: num_cg_steps`¶

`integer :: conv_window`¶

`real(kind=dp) :: conv_tol`¶

`logical :: precond`¶

`real(kind=dp) :: conv_noise_amp`¶

`integer :: conv_noise_num`¶

`integer :: num_dump_cycles`¶

`integer :: num_print_cycles`¶

`logical :: write_r2mn`¶

`logical :: guiding_centres`¶

`integer :: num_guide_cycles`¶

`integer :: num_no_guide_iter`¶

`real(kind=dp) :: trial_step`¶

`real(kind=dp) :: fixed_step`¶

`logical :: use_bloch_phases`¶

`logical :: site_symmetry`¶

`real(kind=dp) :: symmetrize_eps`¶

`integer :: slwf_num`¶

`logical :: slwf_constrain`¶

`real(kind=dp) :: slwf_lambda`¶

`logical :: wannier_plot`¶

`integer :: wannier_plot_list(:)`¶

`integer :: wannier_plot_supercell`¶

`character(len=20) :: wannier_plot_format`¶

`character(len=20) :: wannier_plot_mode`¶

`real(kind=dp) :: wannier_plot_radius`¶

`real(kind=dp) :: wannier_plot_scale`¶

`character(len=20) :: wannier_plot_spinor_mode`¶

`logical :: wannier_plot_spinor_phase`¶

`logical :: bands_plot`¶

`integer :: bands_num_points`¶

`character(len=20) :: bands_plot_format`¶

`integer :: bands_plot_project(:)`¶

`character(len=20) :: bands_plot_mode`¶

`integer :: bands_plot_dim`¶

`logical :: fermi_surface_plot`¶

`integer :: fermi_surface_num_points`¶

`real(kind=dp) :: fermi_energy`¶

`real(kind=dp) :: fermi_energy_min`¶

`real(kind=dp) :: fermi_energy_max`¶