[gmx-developers] Missing things in copy_QMrec?

Gerrit Groenhof ggroenh at gwdg.de
Fri Dec 11 09:39:56 CET 2009

On 11 Dec 2009, at 09:31, Ake Sandgren wrote:

> On Fri, 2009-12-11 at 09:14 +0100, Gerrit Groenhof wrote:
>> Hi Ake,
>> That is weird. the options are not supposed to have an effect on the
>> routines in qm_gamess.c. The only effect is that MM particles might
>> appear that have no charge, which should have no effect on the
>> computation of the wavefunction.
> Remember that this is the qm_gamess from Huub not the original one.
> It generates different gamess input instructions depending on bTS and
> bOPT, as does the qm_gaussian.
>> The option is meant to let the QM program carryout the optimization of
>> the QM subsystem, keeping the MM atoms frozen.
> Ok, MM frozen... That does not happen in Huub's qm_gamess i think. It
> just optimizes everything (if i didn't misunderstand it completely)

I have not seen this interface. The way I set it up for gaussian (but it might be broken), was that gromacs passes coordinates charges and LJ parameters to gaussian. The MM atoms are then kept at ther positions, while the QM atoms optimize. The QM/MM interaction was thus done in gaussian. I don't know about the latest gamess version, but for a simulatanous MM optimization, the complete MM machinery needs to be implemented in the qm program, which I was too much work at the time.

Also, more philosophically maybe, one (or at least I) can argue how useful mimizations are for protein systems.


>> But the convergence was poor, and I no longer believe this is the right
>> way to optimize a structure.
>> I am convinced now I shuld remove these options asap.
> I really need to take a crash course in this area... 
> -- 
> Ake Sandgren, HPC2N, Umea University, S-90187 Umea, Sweden
> Internet: ake at hpc2n.umu.se   Phone: +46 90 7866134 Fax: +46 90 7866126
> Mobile: +46 70 7716134 WWW: http://www.hpc2n.umu.se
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Gerrit Groenhof
MPI biophysical chemistry

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