GW


In order to compute the GW electronic structure of the silane molecule you need to run pw.x, wstat.x and wfreq.x in sequence.


The ground state electronic structure of silane molecule with QE is obtained by running pw.x. The pseudopotential files for Si and H in UPF format can be downloaded from: QE-PP database, or from SG15 database. Check out the pw.x input description in order to generate an input file for QE called pw.in.

Your current working directory should contain these files:
pw.in
H_ONCV_PBE-1.0.upf
Si_ONCV_PBE-1.1.upf

Let's inspect the pw.in file, input for pw.x.

> cat pw.in &control calculation = 'scf' restart_mode = 'from_scratch' pseudo_dir = './' outdir = './' prefix = 'silane' wf_collect = .TRUE. / &system ibrav = 1 celldm(1) = 20 nat = 5 ntyp = 2 ecutwfc = 25.0 nbnd = 10 assume_isolated ='mp' / &electrons diago_full_acc = .TRUE. / ATOMIC_SPECIES Si 28.0855 Si_ONCV_PBE-1.1.upf H 1.00794 H_ONCV_PBE-1.0.upf ATOMIC_POSITIONS bohr Si 10.000000 10.000000 10.000000 H 11.614581 11.614581 11.614581 H 8.385418 8.385418 11.614581 H 8.385418 11.614581 8.385418 H 11.614581 8.385418 8.385418 K_POINTS {gamma}
Run pw.x on 2 cores.

> mpirun -n 2 pw.x -i pw.in > pw.out

The output file pw.out contains information about the ground state calculation.



The static dielectric screening is computed using the projective dielectric eigendecomposition (PDEP) technique. Check out the wstat.x input description and generate an input file for WEST called wstat.in.

Add this file to your current working directory:
wstat.in

Let's inspect the wstat.in file, input for wstat.x.

> cat wstat.in { "input_west": { "qe_prefix": "silane", "west_prefix": "silane", "outdir": "./" }, "wstat_control": { "wstat_calculation": "S", "n_pdep_eigen": 50 } }
Run wstat.x on 2 cores.

> mpirun -n 2 wstat.x -i wstat.in > wstat.out

The output file wstat.out contains information about the PDEP iterations, and the dielectric eigenvalues can be found in the file west_prefix.wstat.save/wstat.json.



The static GW electronic structure is computed treating the frequency integration of the correlation part of the self energy with the Contour Deformation techinique and by computing the dielectric screening at multipole frequencies with Lanczos iterations. Check out the wfreq.x input description and generate an input file for WEST called wfreq.in.

Add this file to your current working directory:
wfreq.in

Let's inspect the wfreq.in file, input for wfreq.x.

> cat wfreq.in { "input_west": { "qe_prefix": "silane", "west_prefix": "silane", "outdir": "./" }, "wstat_control": { "wstat_calculation": "S", "n_pdep_eigen": 50 }, "wfreq_control": { "wfreq_calculation": "XWGQ", "n_pdep_eigen_to_use": 50, "qp_bandrange": [ 1, 5 ], "macropol_calculation": "N", "n_lanczos": 30, "n_imfreq": 200, "n_refreq": 300, "ecut_imfreq": 120.0, "ecut_refreq": 2.0, "n_secant_maxiter": 10 } }
Run wfreq.x on 2 cores.

> mpirun -n 2 wfreq.x -i wfreq.in > wfreq.out

The output file wfreq.out contains information about the calculation of the GW selfenergy, and the corrected electronic structure can be found in the file west_prefix.wfreq.save/wfreq.json.