# Electron poor materials research group Group meeting Dec 2, 2010 Theory- VASP simple GW calculations on Si and GaAs.

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Electron poor materials research group Group meeting Dec 2, 2010 Theory- VASP simple GW calculations on Si and GaAs

 Perform a static calculation on the target structure.  Take the WAVECAR WAVEDER and CHGCAR from the static calculation and then execute the GW calculation.  These runs were done on saguaro using 16 processors.  KPOINT grid: 6X6X6 gamma  Number of Bands: 150

System = Si SIGMA = 0.01 #RECOMMENDED MINIMUM SETUP PREC = NORMAL #PRECISION ENCUT = 320 #LREAL =.FALSE. #.FALSE. MEANS USE RECIPROCAL LATTICE ISMEAR = 0 #USE GAUSSIAN SMEARING LOPTICS =.TRUE. NBANDS = 150

System = GaAs SIGMA = 0.01 #RECOMMENDED MINIMUM SETUP PREC = NORMAL #PRECISION ENCUT = 320 #LREAL =.FALSE. #.FALSE. MEANS USE RECIPROCAL LATTICE ISMEAR = 0 #USE GAUSSIAN SMEARING LOPTICS =.TRUE. NBANDS = 150 ALGO = GW0 NOMEGA = 64 NELM = 4 PRECFOCK=N LSPECTRAL=.TRUE.

 GW run time: 68m6.3s  The average difference between the valence and conduction band in the DFT is: 3.771 eV. Using GW the difference is 4.535 eV. ΔE=4.535 - 3.771 eV = 0.7644.  The Si bandgap according to DFT is E g = 0.5797 eV.  New Gap = ΔE + E g = 1.344 eV ??

 GW run time: 58m13.1s  The average difference between the valence and conduction band in the DFT is: 3.750 eV. Using GW the difference is 4.514 eV. ΔE=4.514 - 3.750 eV = 0.7634.  The GaAs bandgap according to DFT is E g = 0.6035 eV.  New Gap = ΔE + E g = 1.367 eV ??

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