Hi Tram,
To use ev.x, you need a file with the lattice constants and total energies
tabulated.
Here is a shell script that will take an input file, adjust the lattice
parameter over a small range (+/- 2% in my example) and collect the lattice
parameters and total energies in an file I call ev.dat (note you must have sed
and awk available):
#!/bin/sh
EXE=pw.x
IN=
OUT=`echo $IN | sed 's/\.in/\.out/'`
DAT=ev.dat
A0=
for fac in -0.020 -0.015 -0.010 -0.005 0.000 0.005 0.010 0.015 0.020
do
alatt=`echo "$fac $A0" | awk '{printf "%5.3f",(1+$1)*$2}'`
mkdir $alatt
sed "/celldm(1)/s/=.*/= $alatt/" $IN > $alatt/$IN
cd $alatt
$EXE < $IN >& $OUT
e=`grep '! total energy' $OUT | tail -1 | awk '{printf
"%16.10f\n",$5}'`
echo "$alatt $e" >> ../$DAT
cd ..
done
Be sure that the pw.x executable is in your shell path and define your own
input file name and lattice constant. You may also adjust the range you want
to sample for the bulk modulus.
Once, you've run the script to get your energies, run ev.x, choose au as the
units, choose the appropriate cell shape (fcc in your case), put ev.dat as the
input file and name the output whatever you want. Pick the equation of state
you want to use, and the results will appear in the output file you named.
I hope this helps. Anyone with additional and/or corrective advice, please
chime in.
--William
*********************************************************
William D. Parker phone: (630) 252-1775
Computational Postdoctoral Fellow fax: (630) 252-4798
MSD-212, Rm. C-215
Argonne National Laboratory
9700 S. Cass Ave.
Argonne, IL 60439
*********************************************************
On Jan 4, 2011, at 4:06 PM, Tram Bui wrote:
> Hi All,
> Hope everyone had great holidays, I had a question before regarding the
> Bulk Modulus calculation (ev.f90) But I'm having hard time understand the
> file and don't know how to use the ev.f to help me calculate the bulk modulus
> if I have an input file is like below and the structure is zinc blend
> (b-SiC). Would you help me if you get a chance? here is my file and you can
> run it in xcyrsden to see the structure.
>
> &CONTROL
> calculation='scf'
> restart_mode='from_scratch',
> prefix='Silicon',
> tprnfor=.true.
> pseudo_dir='/home/trambui/QE/espresso-4.2.1/pseudo',
> outdir='./tmp7/',
> /
> &SYSTEM
> ibrav=2, celldm(1)=8.33, nat=2, ntyp=2,
> ecutwfc= 30,
> /
> &ELECTRONS
> diagonalization= 'david',
> mixing_mode= 'plain',
> mixing_beta= 0.5,
> conv_thr= 1.0d-7,
> /
> ATOMIC_SPECIES
> Si 28.086 Si.pbe-n-van.UPF
> C 12.011 C.pbe-van_ak.UPF
> ATOMIC_POSITIONS
> Si 0.00 0.00 0.00
> C 0.25 0.25 0.25
> K_POINTS automatic
> 10 10 10 0 0 0
>
> I really appreciate your helps!
>
> Tram Bui
>
> B.S. Materials Science & Engineering
> trambui at u.boisestate.edu
>
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