Accurate quantum-chemical calculations using Gaussian-type geminal and Gaussian-type orbital basis sets : applications to atoms and diatomics

• We have implemented the use of mixed basis sets of Gaussian one- and two-electron (geminal) functions for the calculation of second-order Moller-Plesset (MP2) correlation energies. In this paper, we describe some aspects of this implementation, including different forms chosen for the pair functions. Computational results are presented for some closed-shell atoms and diatomics. Our calculations indicate that the method presented is capable of yielding highly accurate second-order correlation energies with rather modest Gaussian orbital basis sets, providing an alternative route to highly accurate wave functions. For the neon atom, the hydrogen molecule, and the hydrogen fluoride molecule, our calculations yield the most accurate MP2 energies published so far. A critical comparison is made with established MP2-R12 methods, revealing an erratic behaviour of some of these methods, even in large basis sets.

Ämnesord

NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

Nyckelord

molecular correlation energies

2nd-order correlation energies

closed-shell atoms

plesset mp2-r12 calculations

electronic-structure theory

wave-functions

correlation cusp

correlated calculations

perturbation treatment

1st-row atoms

Physics

Fysik

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