PROJECTS

PRINCIPAL INVESTIGATOR

Prof. Dr. Christian Ochsenfeld Eberhard-Karls-Universität Tübingen Physikalische und Theoretische Chemie Auf der Morgenstelle 8 D-72076 Tübingen +49-7071-29-78745 +49-7071-29-5490 christian.ochsenfeld@uni- tuebingen.de

PROJECT RESEARCH ASSISTANT

ABSTRACT

For the reliable calculation of molecular systems with quantum chemical methods electron-correlation effects need often to be accounted for. these can be described within the simplest approach by second-order perturbation theory (MP2). The computational effort of conventional MP2 scales with the fifth power of molecular size, which strongly limits the applicability to molecular systems with more than 100 atoms. For the treatment of larger molecules the reduction of the scaling behavior is crucial, however, despite considerable progress no generally accepted alternative has been established so far, since either the accuracy depends strongly on the molecule or the prefactors of the computational effort have been too large. the main goal of this research proposal is the development of an efficient, linear-scaling method for the calculation of MP2 energies, which allows by rigorously estimating integral contributions to the energy to obtain exactly the same accuracy and reliability as conventional MP2 methods. In this way, we aim for the reliable computation of MP2 energetics for molecular systems with 500-100 and more atoms (without point group symmetry), so that dispersion type interactions can be described for the first time by rigourous ab initio-methods in large molecular systems

PUBLICATIONS

D. S. Lambrecht and C. Ochsenfeld,
Multipole-Based Integral Estimates for the Rigorous Description of
 Distance Dependence in Two-Electron Integrals,
J. Chem. Phys. 123, 184101 (2005)

D. S. Lambrecht, B. Doser and C. Ochsenfeld,
Rigorous Integral Screening for Electron Correlation Methods,
J. Chem. Phys. 123, 184102 (2005)