Introduction

My group focuses on development and application of multiscale and multilevel methods for the description of complex molecular systems. We develop relativistic coupled cluster methods that, for small molecular systems, yield a precise description of electronic structure and molecular properties. This WFT description is incorporated in a subsystem DFT approach in which subsystems are optimized individually and treated as frozen in the embedding of the other subsystems. The motion of subsystems can be studied by adaptive molecular dynamics, in which the QM/MM partitioning of the systems is automatically adjusted during the simulation depending on the distance of subsystems from the active QM center.

With this methodology we tackle a variety of applications: Relativistic calculations serve to benchmark approximate electronic structure methods and to predict molecular properties that are determined by the wave function close to nuclei (NMR shieldings and nuclear spin-spin couplings, splittings due to nuclear quadrupole moments, lifting of degeneracies due to parity violation). In combination with subsystem DFT we can also study actinide ligation and spectroscopy in aqueous environments relevant to the nuclear fuel cycle. The subsystem approaches are used in biomolecular systems to address solvent effects on molecular properties, to obtain detailed potentials for pharmaceutical docking applications and to study the electronic structure of light harvesting complexes.