30 Rydberg at least for wavefunction cutoff and 240 for charge density. On Wed, May 2, 2012 at 9:03 AM, matt reish <reishme04 at gmail.com> wrote: > Thanks for the reply, seemed to be going way too fast for what I had read I > that I should expect. Any thoughts on what would be more reasonable cutoffs > for wavefunction and density? Would it be reasonable to try to attain a > useable result on a "cluster" using 8 processors? > > Cheers, > > Matt > > > On Wed, May 2, 2012 at 3:02 PM, Axel Kohlmeyer <akohlmey at gmail.com> wrote: >> >> On Tue, May 1, 2012 at 10:53 PM, matt reish <reishme04 at gmail.com> wrote: >> > Hi PW list, >> > >> > I am working with Quantum Espresso (v4.3.2.1) in the hopes of attaining >> > Raman phonon frequencies of a benzoic acid crystal. I attained the >> > optimized >> > output geometry from a CASTEP calculation in the supplemental material >> > of a >> > paper. This geometry was used by the authors to calculate accurate IR >> > phonon >> > frequencies. I used a 'relax' calculation in Quantum Espresso on the >> > optimized geometry but this led to large shifts in the atomic positions >> > in >> > the lattice and unreasonable structures for the molecules in the lattice >> > after finding the optimized structure. My question is does anyone have a >> > some experience calculating organic crystals in Quantum Espresso that >> > could >> > give me some tips? >> >> >> matt, >> >> you are using a *ridiculously* low wavefunction >> and density cutoff, that means your basis set >> is *far* too small. unphysical results are the >> logical consequence. >> >> axel. >> >> >> > >> > Here is my input file minus the atomic posititions: >> > >> > &CONTROL >> > ?????????????????????? title = 'benzacidscftest' , >> > ???????????????? calculation = 'relax' , >> > ??????????????? restart_mode = 'from_scratch' , >> > ????????????????????? outdir = '/home/mreish/tmp/' , >> > ????????????????? pseudo_dir = '/usr/share/espresso/pseudo/' , >> > ????????????????????? prefix = 'batest5' , >> > ???????????????????? disk_io = 'default' , >> > ?????????????????????? nstep = 600 , >> > ?/ >> > ?&SYSTEM >> > ?????????????????????? ibrav = 12, >> > ?????????????????????????? A = 5.4996 , >> > ?????????????????????????? B = 5.1283 , >> > ?????????????????????????? C = 21.950 , >> > ?????????????????????? cosAB = 0 , >> > ?????????????????????? cosAC = -.128276341 , >> > ?????????????????????? cosBC = 0 , >> > ???????????????????????? nat = 60, >> > ??????????????????????? ntyp = 3, >> > ???????????????????? ecutwfc = 5 , >> > ???????????????????? ecutrho = 40 , >> > ?/ >> > ?&ELECTRONS >> > ??????????? electron_maxstep = 200, >> > ??????????????????? conv_thr = 1.0d-11 , >> > ?/ >> > ?&IONS >> > ?/ >> > ATOMIC_SPECIES >> > ??? C?? 12.01000? C.pbe-rrkjus.UPF >> > ??? O?? 16.00000? O.pbe-rrkjus.UPF >> > ??? H??? 1.00000? H.pbe-rrkjus.UPF >> > ATOMIC_POSITIONS angstrom >> > >> > K_POINTS automatic >> > ? 1 1 1?? 1 1 1 >> > >> > >> > Cheers, >> > >> > Matthew Reish >> > University of Otago >> > Dunedin >> > New Zealand >> > >> > _______________________________________________ >> > Pw_forum mailing list >> > Pw_forum at pwscf.org >> > http://www.democritos.it/mailman/listinfo/pw_forum >> > >> >> >> >> -- >> Dr. Axel Kohlmeyer >> akohlmey at gmail.com ?http://goo.gl/1wk0 >> >> College of Science and Technology >> Temple University, Philadelphia PA, USA. > > > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum >
-- Regards, MOHNISH, ----------------------------------------------------------------- Mohnish Pandey BTech-Mtech, IIT Kanpur Senior Project Associate, Department of Chemical Engineering, IIT KANPUR, UP, INDIA -----------------------------------------------------------------