Wannier90_SnS2

Wannier90_SnS₂

Input files to calculate the electronic band structure and DoS of SnS₂ using the VASP Wannier90 interface and the PBE and HSE06 functionals and the G₀W₀, scGW₀ and scGW methods.

Running the example

Note: You will need to obtain the Sn_d and S PBE PAW pseudopotentials (POTCAR files) from the VASP database to run these calculations.

1. Perform an ionic relaxation with the experimental lattice parameters using PBEsol with the DFT-D3 dispersion correction and fairly tight convergence criteria.

2. Perform an electronic-structure calculation with PBE:

• Run VASP with the skeleton wannier90.win in the working directory; VASP will add the missing information and will generate several other input files needed by Wannier90.

• Add the additional band-structure tags from wannier90_band.win and run Wannier90 with e.g. wannier90.x wannier90 to calculate the maximally-localised Wannier functions (written towannier90.chk) and the band structure. The result is saved into wannier90_band.dat, wannier90_band.kpt, wannier90_band.gnu for plotting.

• Replace the band-structure tags with the postw90.x tags in wannier90-dos.win and run postw90.x with e.g. mpirun -np 32 postw90.x wannier90 to calculate the DoS. The result is saved into wannier90-dos.dat.

3. Perform an electronic-structure calculation with HSE06. The complete calculation consists of three three parts:

• First, perform an electronic-structure calculation with PBE to obtain converged GGA wavefunctions (this step can be skipped, but should save time).

• Copy the WAVECAR file and use the GGA wavefunctions as an initial guess for an electronic-structure calculation with HSE06.

• Copy the WAVECAR file and re-run VASP with ALGO = None, NELMIN = 0, NPAR = <Default> and LWANNIER90 = .TRUE. to generate Wannier90 input from the converged HSE06 wavefunctions (post-process as in #2).

4. Perform electronic-structure calculations with the GW routines. This calculation is again done in several separate steps:

• First, again perform an electronic-structure calculation with PBE to obtain converged wavefunctions (this is identical to the first step in #3, and can again be skipped if desired).

• Copy the WAVECAR and re-run VASP with ALGO = Exact and LOPTICS = .TRUE. to obtain accurate conduction states and a WAVEDER file.

• For each of the GW calculations (a. G₀W₀, b. scGW₀, c. scGW), copy the WAVECAR and WAVEDER files from the previous step, and run VASP to generate the Wannier90 input from the calculations (again, post-process as in #2).

Links

• http://www.slideshare.net/jmskelton/vasp-and-wannier90-a-quick-tutorial: A brief overview of using the Wannier90 interface with VASP.

• http://wannier.org/user_guide.html: Wannier90 user-guide pages with links to a PDF manual and tutorial.