Response to Geometric Distortions from Atom-Based Relativistic Projection on Electronic States

摘要

We suggest a quasi-relativistic model for molecular electronic structure calculations obtained by an atomic ansatz for the relativistic projection transformation. With such a choice, the projection transformation becomes both transferable and independent of the geometry. The formulation is flexible with regard to the choice of the projection transformation. We employ the free-particle Foldy-Wouthuysen and the Douglas-Kroll second-order variants for the projection coefficients. First results for the diatomic molecules AuH, AuCl, and Au_2 and two structural isomers of Ir_4 suggest the new approximate method as an efficient and accurate replacement for the conventional transformation.