VASP Computing Bulk Modulus of ZrO2 - Revision history

Caiwei at 21:18, 31 December 2008

2008-12-31T21:18:09Z

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	Here we give an example of how to use VASP to compute the bulk modulus of GGA-ZrO2. We performed this calculation on <tt>SU-AHPCRC</tt> in parallel mode (8 CPUs). The running directory contains the following files.		Here we give an example of how to use VASP to compute the bulk modulus of GGA-ZrO2. We performed this calculation on <tt>SU-AHPCRC</tt> in parallel mode (8 CPUs). The running directory contains the following files.

Caiwei at 21:17, 31 December 2008

2008-12-31T21:17:25Z

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	Here we give an example of how to use VASP to compute the bulk modulus of GGA-ZrO2. We performed this calculation on <tt>SU-AHPCRC</tt> in parallel mode (8 CPUs). The running directory contains the following files.		Here we give an example of how to use VASP to compute the bulk modulus of GGA-ZrO2. We performed this calculation on <tt>SU-AHPCRC</tt> in parallel mode (8 CPUs). The running directory contains the following files.

Caiwei: initial copy

2008-12-31T21:16:31Z

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VASP: Computing Bulk Modulus of ZrO2
<DIV>
 
</DIV>

Here we give an example of how to use VASP to compute the bulk modulus of GGA-ZrO2. We performed this calculation on <tt>SU-AHPCRC</tt> in parallel mode (8 CPUs). The running directory contains the following files.

INCAR

<pre>
ZrO2 calculation

ISMEAR = 0
ISIF = 2
PREC = High
</pre>

KPOINTS

<pre>
6x6x6
0 0 = automatic generation of k-points
Monkhorst
6 6 6
0 0 0
</pre>

B.pbs

<pre>
#!/bin/bash
#PBS -N ZrO2_bulk
#PBS -j oe
#PBS -l nodes=1:ppn=8,walltime=6:00:00
#PBS -V

### ---------------------------------------
### BEGINNING OF EXECUTION
### ---------------------------------------

echo The master node of this job is `hostname`
echo The working directory is `echo $PBS_O_WORKDIR`
echo This job runs on the following nodes:
echo `cat $PBS_NODEFILE`

ncpu=`cat $PBS_NODEFILE | wc -w`
echo "Number of processors = $ncpu "

### end of information preamble

cd $PBS_O_WORKDIR

echo $PWD

./auto.B.par $ncpu
</pre>

auto.B.par

<pre>
#!/bin/bash

ncpu=$1

rm WAVECAR
for a in 5.130 5.135 5.140 5.145 5.150 5.155
do
cat > POSCAR << FIN
POSCAR for ZrO2 (created by auto.B.par)
$a
1.00 0.00 0.00
0.00 1.00 0.00
0.00 0.00 1.00
4 8
Direct
0 0 0
0 0.5 0.5
0.5 0 0.5
0.5 0.5 0
0.25 0.25 0.25
0.25 0.25 0.75
0.25 0.75 0.25
0.25 0.75 0.75
0.75 0.25 0.25
0.75 0.25 0.75
0.75 0.75 0.25
0.75 0.75 0.75
FIN

echo "a=$a ncpu=$ncpu"

mpiexec --comm=ib -np $ncpu ../../../bin/vasp

E=`tail -1 OSZICAR`
echo $a $E | sed -s 's/F=//; s/E0=//; s/d E =//;' >> Elatt.B.dat

p=`grep pressure OUTCAR | cut -b 25-34`
echo $a $p >> platt.B.dat

done
</pre>

You also need to put the pseudopotential file (for Zr and O together) as <tt>POTCAR</tt> in this directory. Submit the calculation by

qsub B.pbs

The job will create data files <tt>Elatt.B.dat</tt> and <tt>platt.B.dat</tt>. Similar to the case of Au, we can compute the bulk modulus from these data by fitting the energy - lattice constant relation to a quadratic curve. In this example, the result is a0 = 5.146 angstrom, Ecoh = -9.47 eV, B = 239 GPa. You will need to make <tt>n=12;</tt> and <tt>N=12;</tt> if you want to use Matlab function [[media:fit_a0EB.m.txt | fit_a0EB.m]]. Allowing the Zr and O sub-lattices to relax relative to each other doesn't seem to change the results. Note that in reality the cubic zirconia phase studied here is unstable (against the tetragonal phase). The cubic phase is only stablized if Yttrium dopants are added, forming yttria-stablized-zirconia (YSZ). (See http://www.springerlink.com/content/g72mw270608t757t/fulltext.pdf)