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 ??
