Analytic energy derivatives in relativistic quantum chemistry

Abstract

In this review, we discuss the current status of analytic derivative theory in relativistic quantum chemistry. A brief overview of the basic theory for the available relativistic quantum chemical methods as well as the state‐of‐the‐art development of their analytic energy derivatives is given. Among the various relativistic quantum chemical methods, cost‐effective approaches based on spin separation and/or on the matrix representation of two‐component theory have been proven particularly promising for the accurate and efficient treatment of relativistic effects in electron correlation calculations. We highlight analytic derivative techniques for these cost‐effective relativistic quantum chemical approaches including direct perturbation theory, the spin‐free Dirac‐Coulomb approach, and the exact two‐component theory in its one‐electron variant. An outlook is given on future developments of analytic energy derivative techniques for relativistic quantum chemical methods, again with an emphasis on cost‐effective schemes. © 2014 Wiley Periodicals, Inc.