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.
