This paper describes some numerical experiments in which distributed basis sets of Gaussian s-type functions are used in second-order Møller-Plesset (MP2) perturbation theory approximation to evaluate the correlation energy of electronic ground and excited states. Efficiency of basis sets consisting of s-type functions distributed along the molecular axis supplemented by subsets of the off-axis functions is investigated. We introduce a model where the centers of the off-axis s-Gaussian functions are distributed on the circumferences of circles perpendicular to the molecular axis of a diatomic molecule. A new procedure to remedy computational linear dependences of the basis set is proposed. Preliminary results of calculations for the ground and excited states of the H2, LiH and HeH molecules are reported. It is shown that such sets of distributed s-functions are capable of recovering ~ 97-99% of “exact” second-order correlation energy obtained with the so-called R12-MP2 methods.
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