Bandgap of Si using different DFT+HF methods
Overview > bandgap of Si using different DFT+HF methods > MgO optimum mixing > fcc Ni DOS with hybrid functional > Si bandstructure > List of tutorials
Task
Calculation of the band gap in Si using different DFT+HF schemes (PBE, B3LYP, PBE0, HSE06, and HF).
Input
POSCAR
System: Si 5.430 0.5 0.5 0.0 0.0 0.5 0.5 0.5 0.0 0.5 1 Cartesian 0 0 0 0.25 0.25 0.25
INCAR
## Better preconverge with PBE first ## and use the WAVECAR file as inout for the DFT+HF calculation ## Selects the B3LYP hybrid function #LHFCALC = .TRUE. ; GGA = B3 ; AEXX = 0.2 ; AGGAX = 0.72 #AGGAC = 0.81 ; ALDAC = 0.19 #ALGO = D ; TIME = 0.4 ## Selects the PBE0 hybrid function #LHFCALC = .TRUE. ; #ALGO = D ; TIME = 0.4 ## Selects the HSE06 hybrid function #LHFCALC = .TRUE. ; HFSCREEN = 0.2 ; #ALGO = D ; TIME = 0.4 ## Selects HF #LHFCALC = .TRUE. ; AEXX = 1.0 ; ALDAC = 0.0 ; AGGAC = 0 #ALGO = D ; TIME = 0.4 ## Leave this in ISMEAR = 0 SIGMA = 0.01 GGA = PE
KPOINTS
k-points 0 Gamma 6 6 6 0 0 0
Calculation
- script to extract eigenvalues and calculate the bandgap
homo=`awk '/NELECT/ {print $3/2}' $1`
lumo=`awk '/NELECT/ {print $3/2+1}' $1`
nkpt=`awk '/NKPTS/ {print $4}' $1`
e1=`grep " $homo " $1 | head -$nkpt | sort -n -k 2 | tail -1 | awk '{print $2}'`
e2=`grep " $lumo " $1 | head -$nkpt | sort -n -k 2 | head -1 | awk '{print $2}'`
echo "HOMO: band:" $homo " E=" $e1
echo "LUMO: band:" $lumo " E=" $e2
- type
./gap.sh OUTCAR
- README.txt
For each HF+DFT method (B3LYP, PBE0, HSE06, and HF) compute the bandgap of Si
adopting the following procedure:
i) Perform a standard PBE calculation
ii) Perform a HF+DFT run (VASP reads in the WAVECAR from run (i)
iii) Calculate the value of the bandgap by running the script 'gap':
bandgap = min(cband) - max(vband)
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Overview > bandgap of Si using different DFT+HF methods > MgO optimum mixing > fcc Ni DOS with hybrid functional > Si bandstructure > List of tutorials
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