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?<div>
<br></div><div>Cheers,</div><div><br></div><div>Matt<br><div><br><div class="gmail_quote">On Wed, May 2, 2012 at 3:02 PM, Axel Kohlmeyer <span dir="ltr"><<a href="mailto:akohlmey@gmail.com" target="_blank">akohlmey@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div>On Tue, May 1, 2012 at 10:53 PM, matt reish <<a href="mailto:reishme04@gmail.com" target="_blank">reishme04@gmail.com</a>> wrote:<br>
> Hi PW list,<br>
><br>
> I am working with Quantum Espresso (v4.3.2.1) in the hopes of attaining<br>
> Raman phonon frequencies of a benzoic acid crystal. I attained the optimized<br>
> output geometry from a CASTEP calculation in the supplemental material of a<br>
> paper. This geometry was used by the authors to calculate accurate IR phonon<br>
> frequencies. I used a 'relax' calculation in Quantum Espresso on the<br>
> optimized geometry but this led to large shifts in the atomic positions in<br>
> the lattice and unreasonable structures for the molecules in the lattice<br>
> after finding the optimized structure. My question is does anyone have a<br>
> some experience calculating organic crystals in Quantum Espresso that could<br>
> give me some tips?<br>
<br>
<br>
</div>matt,<br>
<br>
you are using a *ridiculously* low wavefunction<br>
and density cutoff, that means your basis set<br>
is *far* too small. unphysical results are the<br>
logical consequence.<br>
<br>
axel.<br>
<div><div><br>
<br>
><br>
> Here is my input file minus the atomic posititions:<br>
><br>
> &CONTROL<br>
> title = 'benzacidscftest' ,<br>
> calculation = 'relax' ,<br>
> restart_mode = 'from_scratch' ,<br>
> outdir = '/home/mreish/tmp/' ,<br>
> pseudo_dir = '/usr/share/espresso/pseudo/' ,<br>
> prefix = 'batest5' ,<br>
> disk_io = 'default' ,<br>
> nstep = 600 ,<br>
> /<br>
> &SYSTEM<br>
> ibrav = 12,<br>
> A = 5.4996 ,<br>
> B = 5.1283 ,<br>
> C = 21.950 ,<br>
> cosAB = 0 ,<br>
> cosAC = -.128276341 ,<br>
> cosBC = 0 ,<br>
> nat = 60,<br>
> ntyp = 3,<br>
> ecutwfc = 5 ,<br>
> ecutrho = 40 ,<br>
> /<br>
> &ELECTRONS<br>
> electron_maxstep = 200,<br>
> conv_thr = 1.0d-11 ,<br>
> /<br>
> &IONS<br>
> /<br>
> ATOMIC_SPECIES<br>
> C 12.01000 C.pbe-rrkjus.UPF<br>
> O 16.00000 O.pbe-rrkjus.UPF<br>
> H 1.00000 H.pbe-rrkjus.UPF<br>
> ATOMIC_POSITIONS angstrom<br>
><br>
> K_POINTS automatic<br>
> 1 1 1 1 1 1<br>
><br>
><br>
> Cheers,<br>
><br>
> Matthew Reish<br>
> University of Otago<br>
> Dunedin<br>
> New Zealand<br>
><br>
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><br>
<span><font color="#888888"><br>
<br>
<br>
--<br>
Dr. Axel Kohlmeyer<br>
<a href="mailto:akohlmey@gmail.com" target="_blank">akohlmey@gmail.com</a> <a href="http://goo.gl/1wk0" target="_blank">http://goo.gl/1wk0</a><br>
<br>
College of Science and Technology<br>
Temple University, Philadelphia PA, USA.<br>
</font></span></blockquote></div><br></div>
</div>