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Beyond Hartree-Fock: MP2 and Coupled-Cluster Methods for large systems

Christof Hättig

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Forschungszentrum Karslruhe, Institute of Nanotechnology, P. O. Box 3640, D-76021 Karlsruhe, Germany
*

In: *Computational Nanoscience: Do It Yourself!*,
J. Grotendort, S. Blügel, D. Marx (Eds.),
Institute for Advanced Simulation, Forschungszentrum Jülich,
NIC Series, Vol **31**, ISBN 3000173501, (2006).

This chapter reviews briefly the theory of second order Møller-Plesset
perturbation theory (MP2), the approximate coupled-cluster
singles-and-doubles method CC2 and closely related ab initio methods
for calculations on excited states which treat the electron-electron
interaction correctly through second order.
It is shown how the computational costs (CPU time and storage requirements)
can be reduced for these methods by orders of magnitudes using the
resolution-of-the-identity approximation for electron repulsion integrals.
The demands for the auxiliary basis sets are discussed and it is
shown how with optimized basis sets the errors due to this
approximation become insignificant compared to the
usual orbital basis set error.
Furthermore, a parallel implementation of RI-MP2 and RI-CC2
in the TURBOMOLE program package
for distributed memory architectures
(as e.g. clusters of linux boxes) is presented and
some prototypical applications are reviewed.

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