Beskinetics

Advanced Software for the Calculation of Thermochemistry, Kinetics, and Dynamics

Argonne PI: Al Wagner (CHM)

Argonne Collaborating Staff: Stephen Gray (CHM), Ron Shepard

(CHM), and Mike Minkoff (MCS).

The Challenge: There are two challenges this project addresses.

(1) The computationally intensive core of computed rate constants is the Cumulative Reaction Probability (CRP). Almost all reaction rate calculations involve statistical approximations to the CRP. The approximations have been tested on very narrow classes of reactions (primarily those involving atoms reacting with diatomic molecules) because of the computational difficulty of computing the CRP for reactions with larger reactants. We are developing and parallelizing methods for calculating the CRP so as to permit a much wider variety of tests of approximate reaction rate theories.

(2) In developing new methods for the CRP, efficient parallel eigensolvers and linear solvers are needed. The same can also be said for developing better parallel algorithms in other areas of chemical theory, in particular, electronic structure calculations. We have developed a new parallel iterative method for eigensolvers and linear solvers called the Subspace Projected Approximate Matrix (SPAM) method. This subspace method allows the physical insight of the application scientist to be mapped into the numerics used to solve the application problem. SPAM is very general and we are developing and testing its application to chemistry problems such as those requiring CRP or electronic structure calculations.

Argonne’s Role: Both projects above are built on the past efforts of the Chemical Dynamics Program in the Chemistry Division and on a long term collaboration with computational scientists in the Mathematics and Computer Science Division. In addition, both projects are connected to the SciDAC TOPS project that MCS is involved in. The CRP project is based in part on the PETSc library of common mathematical kernels that will migrate into the TOPS library. The SPAM project is being carried out in part as a component of the TOPS development of eigensolvers.

At the SciDAC kickoff meeting of January 15-16, 2002, an overview (ppt) (pdf) of this programm was presented.

There are publications that pertinent to this project and an ftp site. These can all be accessed under either the CRP or the SPAM section of this web site.

A paper (pdf) describing the dispersion fitted finite-difference method.