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. > -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20120502/04b0f844/attachment.htm
