CCL:G: MOPAC/MOZYME PBC calculations

 Sent to CCL by: "Andrew Yeung" []
Thanks for getting back. I'll use the .arc files to generate new MOPAC input files. I suppose that MOPAC calculations are so fast that reading in force constants is not a huge advantage.
I've turned to MOPAC because it is able to perform PBC calculations using semi-empirical hamiltonians, whereas Gaussian 09 is only able to use HF & DFT. Furthermore, G09 does not report enthalpies with a frequency calculation (and that must be done numerically).
 On Sun, 26 Aug 2012 12:12:48 -0400
  "John McKelvey" <owner-chemistry{}>
 Sent to CCL by: John McKelvey [jmmckel]-[]
Have you tried the latest version of Gaussian for all this as I think
 it also contains one of the latest MOPAC versions?
In MOPAC itself you can use the DENOUT keyword to keep a satisfactory current density and then OLDENS to read YOUR_FILENAME.DEN in to start
 a subsequent job.
 You can carve out an input geometry from an archive file
 (YOUR_FILENAME.ARC).  To the best of my knowledge MOPAC does not
 output intermediate geometries, and I am not aware that it outputs a
 Hessian that can be read back in.
Again, Gaussian included version of MOPAC can likely do all you want.
 John McKelvey
 On Fri, Aug 24, 2012 at 6:27 PM, Andrew Yeung <> wrote:
 Sent to CCL by: Andrew Yeung [andrew.yeung^^]
 Hi all
I am doing a few PBC calculations on MOPAC, and I was hoping for some
Since the system is rather large (and I suppose the initial guess is poor), I cannot get SCF convergence unless I use the MOZYME keyword. The online
 manual ( gives some tips on
multi-step jobs (MOZYME for geometry optimization, then MOPAC, then perhaps
Since my jobs have started already (MOZYME then FORCE), I want to let it run, and do the MOPAC equivalent of "geom=allcheck guess=read opt(readfc)" on the resultant output file(s). Is this possible? How else can I start a new calculation based on an old one? Should I edit the archive (.arc) file
 into a new MOPAC input file?
 Thanks for your comments.
 Andrew Yeung
 Donald J. Darensbourg Research Group
 Department of Chemistry, Texas A&M University
 3255 TAMU
 College Station, TX 77843-3255
 Tel: 979 845 4837
Fax: 979 845 0158>;
 John McKelvey
 10819 Middleford Pl
 Ft Wayne, IN 46818
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