Study of the electronic structure of molecules. V. All-electron SCF wavefunction for the ground state of pyrazine

Abstract

In this work we report on all-electron SCF LCAO MO computation for the ground-state wavefunction of the pyrazine molecule (C4H 4N2). As in previous works of this series, we have made use of a "contracted set" of Gaussian functions in order to save computational time. All many-center integrals are accurately computed. The two lone pairs on the nitrogen molecule are quite different in character: The lower one is very little delocalized (1.88 electrons on the nitrogen); the second lone pair is as delocalized as the lone pair in pyridine (1.37 electrons on the nitrogens, 0.22 electrons on the hydrogens, and 0.40 electrons on the carbons). Each of the hydrogen atoms has donated 0.27 electrons to the carbons or the nitrogens of the molecule.