Siddharth Dasgupta

Director, Materials and Molecular Simulation Center
California Institute of Technology
Mail Stop 139-74
Pasadena, CA 91125, USA

(In development)

Accelerated Strategic Computing Initiative (ASCI)

1998 October Site Visit
HighExplosives (HE)

Research interests

Force Fields for Molecular Simulations

The Hessian Biased Force Field (HBFF) Method [J. Chem. Phys. 90, 7207 (1989)] was developed to generate vibratioally accurate force fields for simulation. Recent modifications include the SVD(Singluar Value Decompositon) method for force field optimizations. [J. Chem. Phys. 104, 2898 (1996)]

Proteins and Biological Macromolecules

Using a combination of theory and experiments, we were the first to show that aromatic molecules form hydrogen bonds (weaker than traditional hydrogen bonds) with polar molecules. Both in the water-benzene [Science 257, 942 (1992)] and Ammonia-benzene [Nature 362, 735 (1993)] gas-phase complex, the benzene pi electron density acts as the hydrogen bond acceptor. In recognition and binding of drugs and natural substrates of proteins [see Nature 358, 646 (1992)], these weak aromatic H-bonds play a significant role.

Using a generation 3 force field, we are simulating the quantitive binding properties of a number of biological macromolecules.

Polymers

Using vibrationally accurate force fields, we have simulated the properties of a variety of polymers which include:

Polyethylene-I [J. Phys. Chem. 95, 2260 (1991); Mat. Res. Soc. Symp. Proc. 278, 61 (1992)]
Polyoxymethylene [J. Phys. Chem. 97, 10891 (1993)]
Nylons [J. Am. Chem. Soc. 118, 12291 (1996)]
Polysilane [J. Phys. Chem. 997, 13321 (1995)]
Poly-vinyl fluoride polymers
Poly-vinyl chloride polymers

Molecular Dynamics of Very Large Systems on Massively Parallel Machines

Method MMD [J. Comp. Chem. 18, 501 (1997)] Non-crystalline polymers and viruses are two examples of systems where the simulation size can exceed a million particles. We have developed algorithms to take the architecture of Massively Parallel Machines like KSR1, Intel Paragon and Cray T3D to perform dynamics on a fast time scale.

Gas Diffusion in Polymers [manuscript in perparation] Using short time molecular dynamics with Periodic Boundary Conditions, we extract bulk properties like compressibility and voids and their mobility. This is then used in a Monte Carlo program to simulate the long time diffusion behaviour of several gases. Qualitative trends are in agreement with experimental data, as are quantitative Diffusion Constants.

Mechanism of Organic BEDT-TTF Based Superconductors BEDT-TTF [J. Am. Chem. Soc. 117, 8154 (1995)]

Recent Publications

Originally from INDIA

Home of the Taj Mahal

From the State of - West Bengal