it seems that you don't know how bulk modulus is actually calculated. It is -V(d^2E/dV^2). So you need to vary the volume, calculate total energy then fit the data to equation of states (I think ev.f90 do this job, I am not so sure. But in any case, you can always fit these data to equation of states by any other programs or codes). Once you have equation of states, calculate -V(d^2E/dV^2) at the minimum >>> this is bulk modulus.
I suggest that you should have look a http://www.pwscf.org/wiki/index.php/QESB09 and follow the Lab tutorial on Monday 20, July 2009. The week1_day1_exersice1 is about optimizing lattice parameter, equation of states (that includes bulk modulus) -------------------------------------------------- Duy Le PhD Student Department of Physics University of Central Florida. "Men don't need hand to do things" On Tue, Jan 4, 2011 at 5:06 PM, Tram Bui <trambui at u.boisestate.edu> 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 > > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > >
