Professor James B. Anderson is supported by a grant from the Theoretical and Computational Chemistry Program to explore Green's Function Quantum Monte Carlo techniques for studying chemical systems. Professor Anderson has been using massively parallel computers such as the CM-2 connection machine to perform Green's Function Monte Carlo calculations on simple triatomic systems such as the reaction between hydrogen atoms and hydrogen molecules. In his recent calculations on the complete 4-body hydrogen molecule calculation, he was able to achieve a sustained speed of 1.5 gigaflop on a 65K processor CM-2 computer, with an overall accuracy of 0.006 Kcal/mole. Anderson will study the reaction surfaces for the hydrogen exchange reaction using the same approach, with the expectation of accuracies better than 0.01 Kcal/mole over the entire potential energy surface. He also expects to study the potential energy surface for the flourine atom plus hydrogen molecule reaction. Other systems to be studied include excitons in semiconductor crystallites, extended molecular systems consisting of small polyatomic molecules, and clusters of helium atoms. %%% The calculations which will be done in this project are important because they form an exact benchmark against which other electronic structure theoretical models can be tested.
