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Electronic Structure: Hartree-Fock and Correlation Methods

Christof Hättig

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Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, D-44780 Bochum, Germany
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*Multiscale Simulation Methods in Molecular Sciences*,
J. Grotendort, N. Attig, S. Blügel, D. Marx (Eds.),
Institute for Advanced Simulation, Forschungszentrum Jülich,
NIC Series, Vol **42**, ISBN 978-3-9810843-8-2, pp. 77-120 (2009).

Hartree-Fock theory is the conceptually most basic eletronic structure method
and also the starting point for almost all wavefunction based correlation
methods. Technically, the Hartree-Fock self-consistent field method is
often also the starting point for the development of molecular
Kohn-Sham density functional theory codes.
We will briefly review the main concepts of Hartree-Fock theory and
modern implementations of the Rothaan-Hall self-consistent field equations
with emphasis on the techniques used to make these approaches
applicable to large systems.
The second part of the chapter will focus on
wavefunction based correlation methods for large molecules,
in particular second order M{\o}ller-Plesset perturbation theory (MP2)
and, for calculations on excited states,
the approximate coupled-cluster singles-and-doubles method CC2,
both treating the electron-electron interaction correct 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 shown how these approaches can parallelized
for distributed memory architectures.
Finally a few prototypical applications are reviewed.

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