Hi Marawan,
I ran short DFT/MM tests with Gaussian 09 and Orca 2.8.0, both NPT and NVE, after equilibrating your system with MM for a short while. Looks all good to me, see attachment for in-/output files and a plot of dipole moment. The time dependence of the dipole moment looks reasonable both with Gaussian and ORCA. Results between Gaussian and Orca diverge after a few steps, it should be possible to improve the agreement by tightening the QM code accuracy thresholds. In fact, the Orca simulations heat up slowly. Have a look at the files, you can probably use these as starting / reference points to set up your simulations.
Attached tests are with BLYP/3-21G to save time. But Orca using RI-BLYP/6-31G* looks OK, too. Note that the Ahlrichs RI-J fit sets have not been optimized for 6-31G*. You have to be careful when defining your QM model.
I hope this helps.
All the best,
Andy
On Dec 15, 2012, at 9:16 PM, marawan hussain wrote:
> Hi Andy,
> I'm attaching you the inputs i were using. I'm using identical starting points. Please see if you find some issue, please also consider running them with your settings.
> I appreciate if you consider adding very simple DFT functional (like BLYP, PBE) in the future in AMBER itself.
>
> King regards
> Marawan<Comp_QM-MM_Gaussian_ORCA_2.rar>_______________________________________________
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--
Dr. Andreas W. Goetz
Assistant Project Scientist
San Diego Supercomputer Center
Tel : +1-858-822-4771
Email: agoetz.sdsc.edu
Web : www.awgoetz.de
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Received on Tue Dec 18 2012 - 12:30:02 PST
