Dar Sathya, Starting from version 4.0 there is an additional option for the vc-relaxation that may be worth trying. Just specify cell_dymanics='bfgs' in the &CELL namelist (and ion_dymanics='bfgs' in &IONS) and the optimization will be done with a quasi-newton bfgs algorithm. It has been recently implemented, report to the list in case of problems best regards, stefano PS: as already noticed by others etot_conv_thr = 1.0E-10 and forc_conv_thr = 1.0D-10 are extremely tight thresholds ... Start using the default values and then modify them to get your own feeling on what is a good threshold for your system...
Prasenjit Ghosh wrote: > Dear Sathya, > > I have no experience in using 'vc-relax'.......so I can't help you out > on this. Either you wait for other people's comments or you can search > the pw forum mailing list. There were discussions regarding this > earlier in this forum. I said its tricky because you need to choose > different parameters correctly to reach the minima quickly and > correctly. What I would suggest is to play around with different > parameters for some small system and understand how they affects the > calculation. Later you can go for production run. > > Prasenjit. > > 2008/7/30 sathya subramanyan <sathya_sheela1985001 at rediffmail.com > <mailto:sathya_sheela1985001 at rediffmail.com>> > > > Dear Dr. Prasenjit, > Thank you so much for your reply and the link. > I'm doing the vc-relax calculation but it has > been running for more than 36 hours.Is this why you have mentioned > that vc-relax is tricky ? I have attached the I/P file for > reference and if you could please take a look at it. > I'm also trying the manual relaxation and will > let you know the status of my results. > > INPUT FILE FOR VC-RELAX > > &CONTROL > calculation = "vc-relax" , > restart_mode = 'from_scratch' , > outdir='/home/413107002/tmp/' , > pseudo_dir = '/home/413107002/espresso-4.0.1/pseudo' , > nstep = 1000 , > etot_conv_thr = 1.0E-10 , > forc_conv_thr = 1.0D-10 , > dt = 150 , > / > &SYSTEM > ibrav = 6 , > celldm(1)=7.373 , > celldm(3)=1.065, > nat = 5 , > ntyp = 3 , > ecutwfc = 30.0, > ecutrho = 300.0 , > occupations = 'fixed' , > degauss = 0.00 , > / > &ELECTRONS > conv_thr = 1.0d-10 , > diagonalization = 'david' , > / > &IONS > ion_dynamics = 'damp' > / > &CELL > cell_dynamics = 'damp-w' , > > / > ATOMIC_SPECIES > Pb 207.2 Pb.vdb.UPF > Ti 47.867 Ti.vdb.UPF > O 15.9994 O.vdb.UPF > ATOMIC_POSITIONS > Pb 0.000 0.000 0.000 > Ti 0.500 0.500 0.538 > O 0.500 0.000 0.612 > O 0.000 0.500 0.612 > O 0.500 0.500 0.117 > K_POINTS {automatic} > 4 4 4 1 1 1 > > Thanking you, > > SATHYA SHEELA.S > Grad. Student > Department of Physics > National Institute of Technology > Tiruchirapalli - 620015 > India > > HP > > <http://adworks.rediff.com/cgi-bin/AdWorks/click.cgi/www.rediff.com/signature-home.htm/1050715198 > at Middle5/2208526_2200903/2203540/1?PARTNER=3&OAS_QUERY=null> > > > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org <mailto:Pw_forum at pwscf.org> > http://www.democritos.it/mailman/listinfo/pw_forum > > > > > -- > PRASENJIT GHOSH, > POST-DOC, > ROOM NO: 265, MAIN BUILDING, > CM SECTION, ICTP, > STRADA COSTERIA 11, > TRIESTE, 34104, > ITALY > PHONE: +39 040 2240 369 (O) > +39 3807528672 (M) > ------------------------------------------------------------------------ > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum >
