Derivation of interpretative models for long range electron transfer from constrained density functional theory

The constrained DFT approach of Wu and Van Voorhis is a promising tool for the study of long range biological electron transfers within Marcus theory. This approach allows one to define chemically relevant non-adiabatic states and to compute the three key parameters entering the rate constant expression: the driving force (Delta G degrees), the reorganization energy (lambda) and the electronic coupling H-DA. Here we present the implementation of the method in deMon2k and we then successively use it to derive new parameters for the Pathway model which is one of the most common interpretative models used in biochemistry to relate the H-DA amplitude to the composition of proteins. This original application of CDFT also opens the door towards more elaborate models. (C) 2009 Elsevier B.V. All rights reserved.