VASP Computing Bulk Modulus of ZrO2
VASP: Computing Bulk Modulus of ZrO2
Here we give an example of how to use VASP to compute the bulk modulus of GGA-ZrO2. We performed this calculation on SU-AHPCRC in parallel mode (8 CPUs). The running directory contains the following files.
INCAR
ZrO2 calculation ISMEAR = 0 ISIF = 2 PREC = High
KPOINTS
6x6x6 0 0 = automatic generation of k-points Monkhorst 6 6 6 0 0 0
B.pbs
#!/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
auto.B.par
#!/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
You also need to put the pseudopotential file (for Zr and O together) as POTCAR in this directory. Submit the calculation by
qsub B.pbs
The job will create data files Elatt.B.dat and platt.B.dat. 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 n=12; and N=12; if you want to use Matlab function 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)