16 - Electron poor materials
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Transcript 16 - Electron poor materials
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
Eg= 0.5797 eV.
New Gap = ΔE + Eg = 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
Eg= 0.6035 eV.
New Gap = ΔE + Eg = 1.367 eV ??