[gmx-developers] Question about the QM/MM methods

[Ake Sandgren]

On Fri, 2009-11-13 at 08:39 +0100, Gerrit Groenhof wrote:
> Hi,
> 
> The gamess-uk interface is based on the 6.x version of Gamess-UK. It
> worked via function calls from a linked games-uk library.

> Huub van Dam has been working on a new interface, based on file
> communication. The gaussian interface works like that as well.I was not
> aware there were problems.

I'm using the interface by Huub van Dam since I'm using gamess-uk 8.x.

> >From you emails I infer you have difficulties with the way the
> information is passed on between the mdp file and the qm routines.
> 
> I have hard coded the possibilities for basissets and methods. The
> problem being that basisset specification was different in different
> programs. Thus now the user's input has to be recognized, stored as an
> integer (enum) and then used to create the correct input for a QM routine.
> 
> For writing an interface, I would look at the gaussian.c, focus only on
> the write_gaussian_input, read_gaussian_output, can call_gaussian, whcih
> are used for 'normal' qmmm calculations.

What I'm basically trying to figure out is if there is anything special
that gromacs expects of the qmmm code for the various basisset/methods
combos or if one can take the easiest way and using the (in this case
gamess-uk) defaults and thus specifying as little as possible.

The problem being that I know more or less nothing about the underlying
science.

In other words, take (src/gmxlib/names.c)
const char *eQMmethod_names[eQMmethodNR+1] = {
  "AM1", "PM3", "RHF",
  "UHF", "DFT", "B3LYP", "MP2", "CASSCF","B3LYPLAN",
  "DIRECT", NULL
};

my guess is that this is matched agains users gromacs input in QMmethod.
The question is what gromacs is expecting to happen in the qmmm code for
each of these in some high level description. I could then try to match
that against gamess-uk input data and write a correct translation.

Esp the AM1 and PM3, the rest i think have been able to guess from
reading gamess-uk and gromacs doccos.

-- 
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