PNNL

Abstract

An approach for modeling electron transfer in solids and at surfaces of iron - (oxy- hydr)oxides and other redox active solids has been developed for electronic structure methods (i.e., plane-wave DFT) capable of performing ab initio molecular dynamics eciently with periodic cells and large system sizes while at the same time being accurate enough to be used in the estimation of the electron-transfer coupling matrix element, VAB, and the electron transfer transmission factor, el. This method is an extension of the valence bond theory ET method for molecules and clusters, imple- mented by Dupuis and co-workers and used extensively by Rosso and co-workers, in which scaled corresponding orbitals derived from the Bloch states are used to calculate the o-diagonal matrix elements HAB and SAB. A key development of the present work is the formulation of algorithms to improve of the accuracy of integration of the exact exchange integral in periodic boundary conditions. This method is demonstrated on model systems for electron small polaron transfer in iron-(oxyhydr)oxides, including bare Fe2+{Fe3+ ions, and in [Fe3+(OH2)2(OH)2)]n+ n chains representing the common edge-sharing Fe octahedral motif in these materials.