wannier

Syntax:

wannier <key1> <args1...>  <key2> <args2...>  ...

Note: only available in calculations using the 'wannier' executable.

Description:

Control calculation and output of maximally-localized Wannier functions [19]. The possible <key>'s and their corresponding arguments are:

• localizationMeasure FiniteDifference | RealSpace

  Controls how the localization of the Wannier functions is calculated. The finite-difference reciprocal space measure of Marzari and Vanderbilt (default) is inexpensive, but its error scales as Nkpoints^(-2./3). The real space version is slower but its error scales as exp(-Nkpoints^(1/3)), and is preferable for quantitative applications. Note that the real-space version is not translationally invariant and wraps on a superlattice Wigner-Seitz cell centered at the origin.

• precondition yes|no

  Whether to use an inverse-Hemholtz preconditioner for the minimization. Affects only the FiniteDifference localizationMeasure. (default: no)

• bStart <band>

  For fixed band calculations, 0-based index of lowest band used. The number of bands equals the number of wannier-centers specified. Default: 0. Use in insulator calculations to ignore semi-core orbitals.

• outerWindow <eMin> <eMax>

  Energy window within which bands contribute to wannier functions [25]. bStart is ignored if outerWindow is specified.

• innerWindow <eMin> <eMax>

  Inner energy window within which bands are used exactly [25]. Requires outerWindow, and innerWindow must be its subset.

• frozenCenters <nFrozen> <filename>

  Include frozen Wannier centers imported as unitary rotations from <filename> (.mlwfU output from another wannier run on the same jdftx state), and force the current centers to be orthogonal to the imported ones. Note that all output of this run will include the frozen as well as new centers for convenience.

  Requires innerWindow if outerWindow is present, and the frozen centers must lie entirely within the inner window or fixed band range. (Effectively, the outer window used in generating the frozen centers must be a subset of the present inner window / fixed band range.)

• saveWfns yes|no

  Whether to write supercell wavefunctions in a spherical reciprocal-space basis. Default: no.

• saveWfnsRealSpace yes|no

  Whether to write supercell wavefunctions band-by-band in real space (can be enormous). Default: no.

• saveMomenta yes|no

  Whether to write momentum matrix elements in the same format as Hamiltonian. The output is real and antisymmetric (drops the iota so as to half the output size). Default: no.

• loadRotations yes|no

  Whether to load rotations (.mlwU and .mlwfU2) from a previous Wannier run. Default: no.

• eigsOverride <filename>

  Optionally read an alternate eigenvalues file to over-ride those from the total energy calculation. Useful for generating Wannier Hamiltonians using eigenvalues from another DFT or a many-body perturbation theory code.

• numericalOrbitals <filename>

  Load numerical orbitals from <filename> with basis described in <filename>.header that can then be used as trial orbitals. The reciprocal space wavefunction output of wannier is precisely in this format, so that supercell Wannier calculations can be initialized from previously calculated bulk / unit cell Wannier functions.

• numericalOrbitalsOffset <x0> <x1> <x2>

  Origin of the numerical orbitals in lattice coordinates of the input. The default [ .5 .5 .5 ] (cell center) is appropriate for output from wannier.

• phononSupercell <N0> <N1> <N2>

  If specified, wannier will read in output (phononHsub and phononBasis) of the phonon code with this supercell and output Wannierized electron-phonon matrix elements (mlwfHePh). This file will contain matrices for pairs of cells in the order specified in the mlwfCellMapSqPh output file, with an outer loop over the nuclear displacement modes in phononBasis.

• rSmooth <rSmooth>

  Width in bohrs of the supercell boundary region over which matrix elements are smoothed. If phononSupercell is specified to process phonon quantities, the rSmooth specified here must exactly match the value specified in the calculation in command phonon.

• wrapWignerSeitz yes|no

  If yes, wrap Wannier centers (and atom positions for phonon modes) to a Wigner-Seitz cell so as to minimize the number of cells in the Wannier-basis output. As a consequence, however, minimized Wannier centers may differ from the guesses by some lattice vector. Default: no.

• spinModeAll|Dn|Up

  If Up or Dn, only generate Wannier functions for that spin channel, allowing different input files for each channel (independent centers, windows etc.). Default: All, generate for all spin channels (only valid option for spintype != z-spin).

Properties:

Requires:     (None)

Forbids:     (None)

Allow multiple:    no

Default:     (None)

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