I. Daizadeh et al., CALCULATION OF ELECTRONIC TUNNELING MATRIX ELEMENT IN PROTEINS - COMPARISON OF EXACT AND APPROXIMATE ONE-ELECTRON METHODS FOR RU-MODIFIED AZURIN, The Journal of chemical physics, 106(13), 1997, pp. 5658-5666
In recent years several theoretical methods have been developed for ev
aluation of the magnitude of electronic coupling between distant donor
and acceptor complexes mediated by a protein molecule. Most detailed
studies have been carried out within the one-electron tight-binding (e
xtended Huckel) approximation for electronic structure of the protein
medium. In this paper different approximate and exact one-electron met
hods such as perturbation theory, exact diagonalization, and method of
tunneling currents are reviewed and results of calculations are compa
red for three HisX-Ru-modified azurin molecules, where X=122, 124, and
126. These systems have been recently synthesized and studied experim
entally by Gray and co-workers. The calculations show that perturbatio
n theory results are in excellent agreement with exact calculations if
the symmetry of the zeroth-order wave functions of the donor and acce
ptor metal ions are chosen correctly. A simple computational procedure
for construction of such correct zeroth-order functions is proposed.
(C) 1997 American Institute of Physics.