Subject: Electrost.Pot.Biomol;Graphic Software?

From: <[email-masked]>
Date: Tue, 30 Jan 1996 15:36:08 +0100 (MET)

Dear CCLers,
I'm working on a model to calculate the electrostatic potentials of
Biomolecules, e.g. Proteins.
This model is based on the ADM-model (J.Chem.Phys. 99,1224 (1993)),
which gives you a good approximation of the electrostatic potential
of small molecules.
For this model you need atomic charges and dipole moments (CAMMs),
which have to be calculated from a wavefunction using some population
analysis. In the original ansatz ab initio 6-31G* SCF wavefunctions
were used to calculate the CAMMs with the Mulliken population
analysis.
In my work I'm trying to model these CAMMs (atomic charges and dipoles)
and to use these CAMMs to calculate the electrostatic potentials of
large proteins. In the model, to calculate the CAMMs, intramolecular
polarization is included.
Besides the electrostatic potential the ADM-model also provides
an approximation of the electronic density. Therefore 
the isodensity surfaces of such large molecules are easy to access.
The isodensity surfaces are a valuable tool to interpret the shape
of a system. My aim is to represent the electrostatic potential
of proteins on their isodensity surfaces. Currently the
isodensity surfaces are calculated with the 'Marching Cube'
Algorithm (J.Comp.Chem. 14,246 (1993)). 

Now the questions:

a) The graphical tools I currently use to draw the electrostatic potential
   on the isodensity surfaces are inadequate to use for such a large system 
   as a protein. I'm looking for a graphical device, which is able
   to handle this problem. It should be able to draw the surface triangles
   created by the Marching Cube algorithm at a rate of 10,000 per second.
   
b) I'm looking for a cooperation with somebody, who is interested in
   the application of my model. As input data for the model only
   cartesian coordinates of all atoms (including hydrogen) 
   of a protein are required. As output data you get atomic charges
   and atomic dipole moments. With the ADM-model electrostatic
   potentials on isodensity surfaces can be calculated. Applications
   which directly interpret the electrostatic potential would be nice.
   Currently metal atoms are not feasible.

Heiko Gerwens

Institut fuer Theoretische Chemie 
Universitaet Hannover
Am Kleinen Felde 30
D-30167 Hannover
Germany

email: [email-masked]