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Bader Analysis of FCC Structures: Static Calculations and Insights

This document outlines the methodology and results of static calculations performed on four Face-Centered Cubic (FCC) structures using the VASP software. It details the use of a Gamma 9x9x9 grid and various INCAR settings, including the LAECHG flag to generate charge density outputs. The Bader analysis is conducted on these charge densities, producing multiple output files, essential for understanding the core and atomic charge densities. The results for materials such as GaAs, InSb, GaSb, ZnSe, and ZnTe are analyzed, offering quantitative insights into their electronic properties.

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Bader Analysis of FCC Structures: Static Calculations and Insights

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  1. 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: 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

  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 = 0 #USE GAUSSIAN SMEARING LAECHG=.TRUE.

  5. Electronegativity (EN)using Pauling Scale

  6. GaAs ACF.dat : # 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

  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 -------------------------------------------------------------------------------- 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

  9. GaSb ACF.dat : # 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

  10. ZnSe ACF.dat : # 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

  11. ZnTe ACF.dat : # 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

  12. FCC Comparisons

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