1. Theory- Bader Analysis -> FCC
Electron poor materials research group
Group meeting Nov 11, 2010
Theory- Bader Analysis -> FCC

2. 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:
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

3. 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

4. INCAR_static System = GaAs SIGMA = 0.01 #RECOMMENDED MINIMUM SETUP
PREC = NORMAL #PRECISION
ENCUT = 275
#LREAL = .FALSE #.FALSE. MEANS USE RECIPROCAL LATTICE
ISMEAR = #USE GAUSSIAN SMEARING
LAECHG=.TRUE.

5. Electronegativity (EN) using Pauling Scale

6. GaAs ACF.dat : # X Y Z CHARGE MIN DIST ATOMIC VOL
VACUUM CHARGE:
VACUUM VOLUME:
NUMBER OF ELECTRONS:
ENAs – ENGa = 0.37
Bader charge shift =

7. GaAs Bader Volume Bounding Boxes
All other FCC bounding boxes look virtually identical to this one

8. InSb ACF.dat : # X Y Z CHARGE MIN DIST ATOMIC VOL
VACUUM CHARGE:
VACUUM VOLUME:
NUMBER OF ELECTRONS:
ENSb – ENIn = 0.27
Bader charge shift =

9. GaSb ACF.dat : # X Y Z CHARGE MIN DIST ATOMIC VOL
VACUUM CHARGE:
VACUUM VOLUME:
NUMBER OF ELECTRONS:
ENSb – ENGa = 0.24
Bader charge shift =

10. ZnSe ACF.dat : # X Y Z CHARGE MIN DIST ATOMIC VOL
VACUUM CHARGE:
VACUUM VOLUME:
NUMBER OF ELECTRONS:
ENSe – ENZn = 0.9
Bader charge shift =

11. ZnTe ACF.dat : # X Y Z CHARGE MIN DIST ATOMIC VOL
VACUUM CHARGE:
VACUUM VOLUME:
NUMBER OF ELECTRONS:
ENTe – ENZn = 0.45
Bader charge shift =

12. 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