non collinear case

This page describes the basic workflow of using the VASP2WANNIER90 interface to generate Wannier functions.

⚠️NOTE: For non-collinear case (and calculations with SOC), ISYM=-1 is highly recommended.

Steps

• SCF
• Band_analysis
• Wannierzation

SCF

keywords needed:

LNONCOLLINEAR = .TRUE.
LCHARG = .TRUE.
LWAVE = .TRUE.

keywords optional:

• smearing:

ISMEAR = 0
SIGMA = xxx

• orbital projections:

LORBIT = 11

spin-orbital coupling:

LSORBIT = .TRUE.
ISYM = -1 # turn off symmetry for SOC calculations(optional)

optionally run a spin-polarized calculation (collinear) and save its WAVECAR and CHGCAR for the non-collinear SCF.

Run a spin-degenerate SCF calculation with LNONCOLLINEAR = .TRUE.. This can be done with the non-collinear version vasp_ncl

The goal of this step is to generate self-consistent Bloch wavefunctions (in WAVECAR) and charge density (in CHGCAR).

Band_analysis

keywords needed:

LNONCOLLINEAR = .TRUE.
ICHARG = 11
ISMEAR = 0
SIGMA = xxx
LORBIT = .TRUE.

Then, using p4vasp or pyband you can plot the fat-bands and analysis which bands you want to wannierize and, additionally, the energy windows to use.

Wannierzation

keywords needed:

ISTART = 1
ICHARG = 2
LWANNIER90 = .TRUE.

files needed:

• wannier90.win
• WAVECAR
• CHGCAR
• INCAR
• KPOINTS
• POSCAR
• POTCAR

The wannier90.win file should at least contain:

num_wann        =  ??

begin projections
??
end projections

ISTART=1 and ICHARG=1 tell VASP to read in the Bloch wavefunctions and charge density files. LWANNIER90=.TRUE. tells VASP to run the interface with default specs.

After the job is done, there should be a block in the stdout look like:

 *---------------------------------------*
 *             VASP2WANNIER90            *
 *---------------------------------------*
 *          Non-collinear spin           *
 *            MMN calculated.            *
 *          Projection   1 done.         *
 *          Projection   2 done.         *
 *          Projection   3 done.         *
 *          Projection   4 done.         *
 *          Projection   5 done.         *
 *          Projection   6 done.         *
 *          Projection   7 done.         *
 *          Projection   8 done.         *
 *          Projection   9 done.         *
 *          Projection  10 done.         *
 *          Projection  11 done.         *
 *          Projection  12 done.         *
 *            AMN calculated.            *
 *            EIG written.               *
 *---------------------------------------*

And you should have:

• wannier90.mmn
• wannier90.amn
• wannier90.eig

in your directory.

VASP will automatically fill in other necessary blocks in the wannier90.win file.