Chi Ho Mak is supported by a grant from the Theoretical and Computational Chemistry Program to continue his research in path integral theory of electron transport in chemical and biological systems. Feynman path integral theory is applied in conjunction with Quantum Monte Carlo techniques to the study of the mechanisms for electron transport in a number of molecular electronic systems. The influence of the chemical environment on the motions of the electron is examined in relation to the quantum mechanical features of electron transfer reactions. Various aspects of tunneling, coherence, quantum interference and electron correlation will be studied, and an effort will be made to understand the crossover region between adiabatic and nonadiabatic barrier crossings. Applications include studies of charge separation rate in the bacterial photosynthetic reaction center, a potentially useful molecular quantum interference device, and quantum conductance of one-dimensional molecular wires. The understanding of long-range transport of electrons in molecular systems is of fundamental theoretical importance. It is also one of the key objectives in a rapidly growing area which has become known as molecular electronics. Molecular electronics involves the control of electron flows in molecules through the use of external signals. Work in this area may eventually lead to electronic devices with miniaturization on the order of molecular dimensions.
