Equilibrium volume of Si in the RPA: Difference between revisions
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{{TAGBL|ISMEAR}} = 0 ; {{TAGBL|SIGMA}} = 0.05 | {{TAGBL|ISMEAR}} = 0 ; {{TAGBL|SIGMA}} = 0.05 | ||
{{TAGBL|EDIFF}} = 1E-8 | {{TAGBL|EDIFF}} = 1E-8 | ||
*The following {{TAG| | *The following {{TAG|KPOINTS}} file is used (KPOINTS.12): | ||
12x12x12 | 12x12x12 | ||
0 | 0 | ||
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=== Step 2 === | === Step 2 === | ||
*Compute the Hartree-Fock energy using the DFT orbitals of Step 1. | *Compute the Hartree-Fock energy using the DFT orbitals ({{TAG|WAVECAR}}) of Step 1. | ||
*The {{TAG|INCAR}} file INCAR.EXX is used in this step: | *The {{TAG|INCAR}} file INCAR.EXX is used in this step: | ||
{{TAGBL|ALGO}} = EIGENVAL ; {{TAGBL|NELM}} = 1 | {{TAGBL|ALGO}} = EIGENVAL ; {{TAGBL|NELM}} = 1 | ||
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{{TAGBL|KPAR}} = 8 | {{TAGBL|KPAR}} = 8 | ||
{{TAGBL|NBANDS}} = 4 | {{TAGBL|NBANDS}} = 4 | ||
*{{TAG|NKRED}}=2 is used for the downsample the k-space representation of the Fock-potential to save time. | |||
*Using {{TAG|NBANDS}}=4 only occupied states are considered to save time. | |||
=== Step 3 === | |||
*DFT groundstate calculation with a “coarse” mesh of k-points. | |||
*The following {{TAG|INCAR}} file is used (INCAR.DFT): | |||
{{TAGBL|ISMEAR}} = 0 ; {{TAGBL|SIGMA}} = 0.05 | |||
{{TAGBL|EDIFF}} = 1E-8 | |||
*The following coarse {{TAG|KPOINTS}} file is used (KPOINTS.12): | |||
6x6x6 | |||
0 | |||
G | |||
6 6 6 | |||
0 0 0 | |||
---- | ---- | ||
== Used INCAR Tags == | == Used INCAR Tags == | ||
Revision as of 10:02, 3 April 2018
Overview > bandgap of Si in GW > bandstructure of Si in GW (VASP2WANNIER90) > bandstructure of SrVO3 in GW > CRPA of SrVO3 > Equilibrium volume of Si in the RPA > List of tutorials
Task
Calculation of the equilibrium lattice constant of Si in the RPA (ACFDT).
Input
POSCAR
system Si 5.8 0.5 0.5 0.0 0.0 0.5 0.5 0.5 0.0 0.5 2 cart 0.00 0.00 0.00 0.25 0.25 0.25
Calculation
The workflow of RPA total energy calculations consists of five consecutive steps:
- Step 1: a “standard” DFT groundstate calculation with a “dense” mesh of k-points.
- Step 2: compute the Hartree-Fock energy using the orbitals of Step 1. Needs WAVECAR file from step 1.
- Step 3: a “standard” DFT groundstate calculation with “coarse” mesh of k-points.
- Step 4: obtain DFT “virtual” orbitals (empty states). Needs WAVECAR file from step 3.
- Step 5: the RPA correlation energy (ACFDT) calculation. Needs WAVECAR and WAVEDER files from step 4.
In case of metallic systems there is an additional step between Steps 4 and 5, that is beyond the scope of this example.
All of the calculation steps are prepared in the script doall.sh.
Step 1
- DFT groundstate calculation with a “dense” mesh of k-points
- The following INCAR file is used (INCAR.DFT):
ISMEAR = 0 ; SIGMA = 0.05 EDIFF = 1E-8
- The following KPOINTS file is used (KPOINTS.12):
12x12x12 0 G 12 12 12 0 0 0
Step 2
- Compute the Hartree-Fock energy using the DFT orbitals (WAVECAR) of Step 1.
- The INCAR file INCAR.EXX is used in this step:
ALGO = EIGENVAL ; NELM = 1 LWAVE = .FALSE. LHFCALC = .TRUE. AEXX = 1.0 ; ALDAC = 0.0 ; AGGAC = 0.0 NKRED = 2 ISMEAR = 0 ; SIGMA = 0.05 KPAR = 8 NBANDS = 4
- NKRED=2 is used for the downsample the k-space representation of the Fock-potential to save time.
- Using NBANDS=4 only occupied states are considered to save time.
Step 3
- DFT groundstate calculation with a “coarse” mesh of k-points.
- The following INCAR file is used (INCAR.DFT):
ISMEAR = 0 ; SIGMA = 0.05 EDIFF = 1E-8
- The following coarse KPOINTS file is used (KPOINTS.12):
6x6x6 0 G 6 6 6 0 0 0
Used INCAR Tags
AEXX, AGGAC, ALDAC, ALGO, EDIFF, ISMEAR, KPAR, LHFCALC, LOPTICS, LWAVE, NBANDS, NELM, NKRED, NOMEGA, SIGMA, SYSTEM
Download
Overview > bandgap of Si in GW > bandstructure of Si in GW (VASP2WANNIER90) > bandstructure of SrVO3 in GW > CRPA of SrVO3 > Equilibrium volume of Si in the RPA > List of tutorials
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