Nonequilibrium atomic limit for transport and optical response of molecular junctions

Theoretical tools employed in ab initio simulations in the field of molecular electronics combine methods of quantum chemistry and mesoscopic physics. Traditionally these methods are formulated in the language of effective single-particle orbitals. We argue that in many cases of practical importance a formulation in the language of many-body states is preferable. We review methods of the nonequilibrium atomic limit and our contributions to their development and applications. In particular, model and ab initio simulations of quantum transport and optical response in molecular junctions illustrate the convenience and importance of the methodology. Results of ab initio simulations are compared with experimental data.