Correlation Energy Estimators based on Møller-Plesset Perturbation Theory

Abstract

Some methods for the convergence acceleration of the Møller-Plesset perturbation series for the correlation energy are discussed. The order-by-order summation is less effective than the Feenberg series. The latter is obtained by renormalizing the unperturbed Hamilton operator by a constant factor that is optimized for the third order energy. In the fifth order case, the Feenberg series can be improved by order-dependent optimization of the parameter. Alternatively, one may use Pad{é} approximants or a further method based on effective characteristic polynomials to accelerate the convergence of the perturbation series. Numerical evidence is presented that, besides the Feenberg-type approaches, suitable Pad{é} approximants, and also the effective second order characteristic polynomial, are excellent tools for correlation energy estimation.

21 pages, 87 references, LaTeX2e, elsart.cls, uuencoded compressed tar file created by csh script uufiles. J. Mol. Struct. (THEOCHEM), in press. Postscript and dvi also available via http://www.chemie.uni-regensburg.de/preprint.html and ftp://rchs1.uni-regensburg.de/pub/preprint/TC-QM-96-1