Transcript FCC - Electron poor materials

Electron poor materials research group
Group meeting Nov 11, 2010
Theory- Bader Analysis -> FCC
Procedure
• Static Calculations of the 4 FCC structures were computed
– Calculations were done on a Gamma 9X9X9 grid
– An extra flag was used in the INCAR file: LAECHG = .TRUE.
•
•
•
•
Turns on All Electron CHGCAR file outputs and outputs 3 files
AECCAR0: core charge density
AECCAR1: atomic AE charge density (overlapping atomic charge density)
AECCAR2: AE charge density
• The files AECCAR0 and AECCAR2 are added together for bader
analysis per instructions:
http://theory.cm.utexas.edu/bader/vasp.php
– chgsum.sh AECCAR0 AECCAR2, chsum is a shellscript
• Outputs CHGCAR_sum
• Bader analysis is done on the vasp CHGCAR from the static run
– bader.x -p atom_index -p bader_index CHGCAR -ref CHGCAR_sum
• atom_index: Write the atomic volume index to a charge density file
• bader_index: Write the Bader volume index to a charge density file
NOTES
• Only the PAW potentials can output there core charges for bader
analysis
• A fine fft grid is needed to accurately reproduce the correct total
core charge. It is essential to do a few calculations, increasing
NG(X,Y,Z)F until the total charge is correct.
• The outputs from bader.x are:
– ACF.dat – Atomic Coordinate file. Shows the location and charge of the
atoms
– BCF.dat – Bader Coordinate file.
– AVF.dat – Atomic Volume file. Used to keep track of other files that may
be output with the bader program with flag –p all_atom
– AtIndex.dat (only with –p atom_index) – charge density file which
contains the atomic borders
– BvIndex.dat (only with –p bader_index) –charge density file which
contains the bader borders
INCAR_static
System = GaAs
SIGMA = 0.01
#RECOMMENDED MINIMUM SETUP
PREC = NORMAL
#PRECISION
ENCUT = 275
#LREAL = .FALSE.
#.FALSE. MEANS USE RECIPROCAL LATTICE
ISMEAR = 0
#USE GAUSSIAN SMEARING
LAECHG=.TRUE.
Electronegativity (EN)
using Pauling Scale
ACF.dat :
GaAs
#
X
Y
Z
CHARGE MIN DIST ATOMIC VOL
-------------------------------------------------------------------------------1
0.0000
0.0000
0.0000
2.2907
0.8192 16.8049
2
1.4133
1.4133
1.4133
5.7093
1.0377 28.3647
-------------------------------------------------------------------------------VACUUM CHARGE:
0.0000
VACUUM VOLUME:
0.0000
NUMBER OF ELECTRONS:
8.0000
ENAs – ENGa = 0.37
Bader charge shift = 0.7093
GaAs Bader Volume Bounding Boxes
All other FCC bounding boxes
look virtually identical to this
one
ACF.dat :
InSb
#
X
Y
Z
CHARGE MIN DIST ATOMIC VOL
-------------------------------------------------------------------------------1
0.0000
0.0000
0.0000
2.7177
1.1221 28.7015
2
1.6196
1.6196
1.6196
5.2823
1.2174 39.2663
-------------------------------------------------------------------------------VACUUM CHARGE:
0.0000
VACUUM VOLUME:
0.0000
NUMBER OF ELECTRONS:
8.0000
ENSb – ENIn = 0.27
Bader charge shift = 0.2823
ACF.dat :
GaSb
#
X
Y
Z
CHARGE MIN DIST ATOMIC VOL
-------------------------------------------------------------------------------1
0.0000
0.0000
0.0000
2.8499
0.9801 22.0766
2
1.5240
1.5240
1.5240
5.1501
1.1732 34.5544
-------------------------------------------------------------------------------VACUUM CHARGE:
0.0000
VACUUM VOLUME:
0.0000
NUMBER OF ELECTRONS:
8.0000
ENSb – ENGa = 0.24
Bader charge shift = 0.1501
ACF.dat :
ZnSe
#
X
Y
Z
CHARGE MIN DIST ATOMIC VOL
-------------------------------------------------------------------------------1
0.0000
0.0000
0.0000 11.3512
0.9048 16.2281
2
1.4218
1.4218
1.4218
6.6488
1.1507 29.7541
-------------------------------------------------------------------------------VACUUM CHARGE:
0.0000
VACUUM VOLUME:
0.0000
NUMBER OF ELECTRONS:
18.0000
ENSe – ENZn = 0.9
Bader charge shift = 0.6488
ACF.dat :
ZnTe
#
X
Y
Z
CHARGE MIN DIST ATOMIC VOL
-------------------------------------------------------------------------------1
0.0000
0.0000
0.0000 11.5271
0.8809 18.6275
2
1.5258
1.5258
1.5258
6.4729
1.2743 38.2015
-------------------------------------------------------------------------------VACUUM CHARGE:
0.0000
VACUUM VOLUME:
0.0000
NUMBER OF ELECTRONS:
18.0000
ENTe – ENZn = 0.45
Bader charge shift = 0.4729
FCC Comparisons
Compound Name
EN2-EN1
Bader
GaSb
0.24
0.1501
InSb
0.27
0.2823
GaAs
0.37
0.7093
ZnTe
0.45
0.4729
ZnSe
0.9
0.6488