PROJECTS

One- to four-component correlated relativistic electronic structure methods based on density matrix renormalization group techniques

PRINCIPAL INVESTIGATOR

PD Dr. Markus Reiher Universität Erlangen Theoretische Chemie Egerlandstraße 3 D-91058 Erlangen +49-(0)9131-85-28646 +49-(0)9131-85-27736 Markus.Reiher@chemie.uni-erlangen.de

PROJECT RESEARCH ASSISTANT

ABSTRACT

Relativistic ab initio methods for molecular systems, which take the correlation of electrons into account (such as the standard configuration interaction or coupled cluster models), have become available during the last decade. It has soon been realized that these highly accurate relativistic methods are extremely computer resource demanding and are presently only applicable for molecules consisting of not more than two heavy atoms. From a different field, namely theoretical solid state physics, a new correlation technique, which is called the Density Matrix Renormalization Group (DMRG) algorithm, was established. It is based on an iterative renormalization of the Hilbert space describing the system under consideration. Only in recent years this technique has been applied to light 'non-relativistic' diatomics. It is planned to extend and improve on these results in order to tackle a large number of active electrons and orbitals as they occur in 'relativistic' molecules. The first step shall be undertaken in a one-component framework as defined by the Douglas-Kroll (DK) approach. In the second step the standard DK frame is extended to include spin-orbit coupling (to higher orders) in combination with DMRG: it is planned to set up an efficient two-component method, which can challenge four-component theories. But also four-component methods shall be tested in (a third step) in combination with the DMRG algorithm.