CCL:G: Facing difficulty in running g03 peogramm

 Sent to CCL by: Errol Lewars [elewars%%trentu.ca]
 2013 Jan 30
First, does your system calculate anything faster than a "very long time"? I found that on an aging computer the parent coumarin (C9H6O2, 11 heayy atoms--a quick indication of "size") took 7 minutes for a HF/6-31G* and 8 minutes for a B3LYP/6-31G* opt/freq.
Second, the time for a job depends heavily on the method (HF, DFT and the functional, MP2, CCSD(T), etc., etc.) and the basis set (6-31G*, 6-311+G**, etc., etc.). You might start with a modest method/basis like HF/6-31G* and expect the time to rise steeply with significant increases in the computational level.
And of course you have to decide from the literature or your experimentation what accuracy in dipole moment you need. 
 E.Lewars
 ==
 Mehboob Alam mehboob.cu(~)gmail.com wrote:
 
 Hi Manjunath Wari,
I'll suggest that you to use all the processors present in your CPU (eg. for quadcore system you can use %nprocshared=4 as the first line of your input). And if you are running parallel then use lindaworkers to call several (available) nodes for your job. It will surely increase the speed of your calculations. %nprocshared keyword can be used for both serial and parallel jobs. 
 Hope it will help.
 With best regards,
 Mehboob
On Tue, Jan 29, 2013 at 7:44 PM, Gkourmpis, Thomas Thomas.Gkourmpis,borealisgroup.com <http://borealisgroup.com>; <owner-chemistry.:.ccl.net <mailto:owner-chemistry.:.ccl.net>> wrote: 
     James what you are asking is impossible to answer as it depends on
     a number of parameters like the type of computer you use, the size
     of your system and the level of accuracy (theory and/or basis set)
     you want your results to have.
     Traditionally for the same system and basis set HF is faster than
     DFT and DFT is faster than CCSD (the later one coincidentally is
     an expensive method)
     I am sorry I cannot provide a more comprehensive answer but in
     reality you are constrained by the parameters I have outlined above.
     Regardless I hope this helps
     Thomas
     Thomas Gkourmpis
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     *Sent:* Monday, January 28, 2013 8:30 PM
     *To:* Gkourmpis, Thomas
     *Subject:* CCL:G: Facing difficulty in running g03 peogramm
     What method are you using (e.g. HF, DFT, CCSD, etc)?  This can
     make a big difference in the run-time. Also what qualifies as a
     "very long time"?
     James
     --
     Dr. J. D. Whitfield
     VCQ Postdoctoral Fellow
     Vienna Center for Quantum Science and Technology
     email: james.whitfield() univie.ac.at
     <mailto:james.whitfield%28%29%20univie.ac.at>
     web: homepage.univie.ac.at/james.whitfield
     <http://homepage.univie.ac.at/james.whitfield>;
     On Mon, Jan 28, 2013 at 12:03 PM, Manjunath Ningappa Wari
     sm5wari^^^gmail.com <http://gmail.com>; <owner-chemistry() ccl.net
     <mailto:owner-chemistry%28%29%20ccl.net>> wrote:
     Sent to CCL by: "Manjunath Ningappa Wari" [sm5wari^^gmail.com
     <http://gmail.com>;]
     I am calculating dipole moment in ground state for coumarine
     molecules using
     g03 program. It is taking very long time to calculate, so plz
     suggest me how to
     run faster the g03 program.
     Thanking you
     Manjunath Wari
     Dept of Physics
     Karnatk University
     Dharwad.
     e-mail: sm5wari_._gmail.com <http://gmail.com>;
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