Slater and Gaussian, 1s orbital functions, for getting a molecular electronic wave?function approximation. Comments on the methodology for evaluating multi?center integrals

J. E. PÉREZ; A. BOUFERGUENE; J. C. CESCO; P. HOGGAN

Buenos Aires

Congreso; Molecular Electronic Structure Conference; 2016

UBA

A basis set composed only of 1sSlater and 1s Gaussian orbitals, is devised for modelling, as close aspossible, the intuitive physicochemical functions, i.e. inner shells, bonds andlone pairs. The STO are introduced at the nucleus for improving the inner shelldescription together with a few GTO. The other GTO, to be used, are aligned on a kind of arms, withthe main objective of describing the directional response of the valenceelectrons to the local electric fields around the particular nucleus in a givenmolecular environment. The geometrical GTO arrangement and the inner shellconfiguration are calibrated for each particular free atom, using theVariational Theorem [1]; the Regular Polytopes interpretation is adopted [2].Examples of molecular systems which show the last version of this model arepresented; all the calculations are performed at the level of LCAO-SCFapproximation. The current research in our group, on new algorithms to evaluatethe multi-centre integrals needed, is presented. The cases involving seriesexpansions and rational approximants are discussed.