Subject: Flexible MD code wanted

From: Guenter Kaeb <[email-masked]>
Date: Tue, 13 Apr 1999 13:34:45 +0200 (MESZ)

Dear CCLers,

 I would be very glad if somebody could point me to freely available MD code
(Fortran 90 or C) which is flexible enough to treat general interaction
potentials between molecular degrees of freedom. General properties should
in principle comprise the following features:

Our specific aim is to simulate by molecular dynamics (completely classical
in the initial stage) the vibrational cooling process of a small linear
triatomic in an atomic (rare gas) solvent.
The complete nuclear potential energy surface for the triatomic (CO2) known from
high-resolution vibrational spectroscopy is of high accuracy involving
polynomial expansion terms up to the sixth order and should ideally be fully
included. Of special importance are the off-diagonal terms in the Hamiltonian
which lead to energy exchange between vibrational modes.
Such coupling terms are, however, rarely included in general purpose MD programs
suited to treat large (bio-)molecules and complex solvents for which detailed
information on molecular interaction terms going beyond harmonic or Morse
potentials is seldom available or not needed to describe structures and
processes of interest.

What we are looking for is MD code, which is suited to address smaller molecules
in simpler solvents, but with higher accuracy.
As stated above, intramolecular potentials should go beyond non-interacting
localized bonding terms. Also, van der Waals pairwise interaction potentials
for solvent sites should be able to involve more parameters than e.g. the
well-known Lennard-Jones potential.

In the most general case, the forces may be derived numerically from the
potentials specified as input. It would be nice, however, to evaluate forces
analytically were possible, which is quite easy for polynomial expansions
mentioned above, and more accurate of course.

Knowing that the complete list of properties is probably not realized by any
existing AND freely available MD package without the need for additional
programming and modification for our own purposes, I would be glad to receive
information on any modularly designed package or bunch of routines which would
allow for more or less "straightforward" adaptation without having to program
from scratch basic standard MD ingredients such as periodic boundaries (cubic
will be sufficient) or ensemble realizations (NVE, NpT, ...) etc.

Finally, I am looking forward to hearing from you!

Kind regards, Guenter Kaeb

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=                                                                            =
=  Dr. Guenter Kaeb                                                          =
=  Max-Planck-Institute of Biophysical Chemistry                             =
=  (Department 010: Spectroscopy and photochemical kinetics)                 =
=  Am Fassberg 11                                                            =
=  D-37077 Goettingen                                                        =
=                                                                            =
=  Tel.: +49-551/201-1344                                                    =
=  Fax:  +49-551/201-1006                                                    =
=                                                                            =
=  e-mail: [email-masked]                                                     =
=                                                                            =
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