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Research areas of the Institute of Theoretical Chemistry

The Institute of Theoretical Chemistry performs method development in ab initio quantum chemistry in the fields of electron correlation and relativistic contributions. The group of Michael Dolg is developing the so-called incremental scheme for accounting for electron correlation effects at the CCSD(T) and F12-CCSD(T) levels for larger molecules. In addition the generation of energy-consistent relativistic ab initio pseudopotentials and corresponding valence basis sets for heavy elements is further pursued. The newest generation of pseudopotentials is based on multi-configuration Dirac-Hartree-Fock reference data based on the finite nucleus Dirac-Coulomb Hamiltonian with a pertubative treatment of the Breit interaction, and for superheavy elements also low-order effects from quantum electrodynamics such as vacuum polarization and electron self-energy. Further studies concern the electronic structure of molecular Ce(III)-based Kondo-type systems such as cerocene, the hydration of lanthanide and actinide ions, titanocene-catalyzed 3- and 4-exo-cyclizations and the haptotropic rearrangement of M(CO)3 fragments on aromatic ?-systems.

The group of Michael Hanrath is involved in the development of methods and program packages for highly accurate multi-reference coupled cluster treatments (MRexpT) as well as for coupled cluster with high degree of excitation operators (CCSDT, CCSDTQ, CCSDTQP, etc.). Besides these, new algorithms for the efficient generation of two-electron intergrals for contracted basis sets as well as new schemes for performing self-consistent field calculations for larger systems are worked on and incorporated into the in-house ab initio program package QOL (quantum object library).

Xiaoyan Cao and coworkers are investigating by computational chemistry the separation of lanthanides from actinides during the workup of nuclear waste using liquid-liquid extractions with, e.g., the cyanex 301 or other macrocyclic ligands. The properties of gadolinium and lutetium complexes with texaphyrin and its derivatives, which have a variety of applications in medicine (e.g. as photosensitizers in photodynamic therapy), are also investigated.