LWANNIER90

LWANNIER90 = .TRUE. | .FALSE.
Default: LWANNIER90 = .FALSE.

Description: LWANNIER90=.TRUE. switches on the interface between VASP and WANNIER90.

N.B.: This feature is only present if VASP is compiled with -DVASP2WANNIER90 or -DVASP2WANNIER90v2.

For LWANNIER90=.TRUE., VASP will write the input files for a WANNIER90 run: wannier90.win, wannier90.mmn, wannier90.eig, wannier90.amn, and if LWRITE_UNK=.TRUE. wannier90.UNKp.s. This is done by running wannier_setup in library mode as described in Chapter 6 of the WANNIER90 manual. For documentation of these files and tags therein, please refer to the WANNIER90 manual.

The following cases may occur:

If wannier90.win does not exist, VASP will write the following template

num_wann = NBANDS

begin unit_cell_cart
  ... ... ...
  ... ... ...
  ... ... ...
end unit_cell_cart

begin atoms_cart
   ... ... ...
   ... ... ...
   ... ... ...
   ... ... ...  
end atoms_cart

mp_grid = .. .. ..

begin kpoints
   ... ... ...
   ... ... ...
   ... ... ...
   ... ... ...
end kpoints

Here, the unit_cell_cart, atoms_cart, and kpoints blocks, and mp_grid array, will be set in accordance with the setup of the VASP calculation. This basically corresponds to the information given in the POSCAR and KPOINTS files.

If the wannier90.win file already exists, VASP will only add the aforementioned information if it is not already present. This means that VASP will check, for instance, whether or not the wannier90.win file contains a kpoints block, and add one if not. Mind: If it finds a kpoints block, VASP will not check whether this block agrees with the k points used in the VASP calculation!

The user may create a wannier90.win file prior to running VASP with LWANNIER90=.TRUE., and specify any tag and/or block that is understood by wannier_setup and/or wannier_run. For instance, one can specify the projections block in the wannier90.win file that controls the initial guess for the maximally localized Wannier functions. Then, VASP writes the projections of the Bloch functions onto the relevant projectors to the wannier90.amn file. See Chapter 3 of the WANNIER90 manual for more information.

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