Fcc Si: Difference between revisions
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*Fcc Si lattice constant of 3.9 <math>\AA</math>. | |||
*1 atom per unit cell. | |||
=== {{TAG|INCAR}} === | === {{TAG|INCAR}} === | ||
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11 11 11 | 11 11 11 | ||
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*Equally spaced k mesh. | |||
*Odd number of k points in each direction results in a <math>\Gamma</math> centered mesh. | |||
*56 k points in IBZ. | |||
== Calculation == | == Calculation == | ||
*Calculate energy for different lattice parameters. | |||
*Fit to some equation of states to obtain the equilibrium volume. | |||
*The bash-script <tt>loop.sh</tt> runs fcc Si at several different lattice constants (3.5-4.3 Å) and collects free energy versus lattice constant into the file SUMMARY.fcc | *The bash-script <tt>loop.sh</tt> runs fcc Si at several different lattice constants (3.5-4.3 Å) and collects free energy versus lattice constant into the file SUMMARY.fcc |
Revision as of 14:07, 4 May 2017
Overview > fcc Si > fcc Si DOS > fcc Si bandstructure > cd Si > cd Si volume relaxation > cd Si relaxation > beta-tin Si > fcc Ni > graphite TS binding energy > graphite MBD binding energy > graphite interlayer distance > List of tutorials
Task
Lattice constant optimization for fcc Si.
Input
POSCAR
fcc Si: 3.9 0.5 0.5 0.0 0.0 0.5 0.5 0.5 0.0 0.5 1 cartesian 0 0 0
- Fcc Si lattice constant of 3.9 .
- 1 atom per unit cell.
INCAR
System = fcc Si ISTART = 0 ; ICHARG = 2 ENCUT = 240 ISMEAR = 0; SIGMA = 0.1
- Initial charge density form overlapping atoms.
- Energy cutoff of 240 eV from POTCAR file.
KPOINTS
k-points 0 Monkhorst Pack 11 11 11 0 0 0
- Equally spaced k mesh.
- Odd number of k points in each direction results in a centered mesh.
- 56 k points in IBZ.
Calculation
- Calculate energy for different lattice parameters.
- Fit to some equation of states to obtain the equilibrium volume.
- The bash-script loop.sh runs fcc Si at several different lattice constants (3.5-4.3 Å) and collects free energy versus lattice constant into the file SUMMARY.fcc
#! /bin/bash BIN=/path/to/your/vasp/executable rm WAVECAR SUMMARY.fcc for i in 3.5 3.6 3.7 3.8 3.9 4.0 4.1 4.2 4.3 ; do cat >POSCAR <<! fcc: $i 0.5 0.5 0.0 0.0 0.5 0.5 0.5 0.0 0.5 1 cartesian 0 0 0 ! echo "a= $i" ; mpirun -np 2 $BIN E=`awk '/F=/ {print $0}' OSZICAR` ; echo $i $E >>SUMMARY.fcc done cat SUMMARY.fcc
Mind: You will have to set the correct path to your VASP executable (i.e., BIN), and invoke VASP with the correct command (e.g., in the above: mpirun -np 2).
- To make a quick plot of SUMMARY.fcc try:
gnuplot gnuplot> plot "SUMMARY.fcc" using ($1):($4) w lp
Download
To the list of examples or to the main page