AbstractsIt is proved that in general the INDO approximation to the full Roothaan theory does not lead to expressions which are invariant under a rotation of local atomic axes. However, when only s-and p-functions are used in the atomic basis set, the equations obtained are invariant due to the special properties of the p-functions. #en d-orbitals are included into the basis set, rotational invariance is lost but can be restored if a supplementary approximation is introduced.11 est dtmontrt, qu'en gtntral I'approximation INDO de la thtorie de Roothaan ne mbne pas i d e s expressions qui sont invariantes par rapport ? i une rotation des axes atomiques locaux. Cepedant, quand on n'emploie que des fonctions s et p, les Cquations sont invariantes grPce aux proprittts particulibres des fonctions p . Quand on utilise aussi des orbitales d, I'invariance rotationnelle est perdue, mais elle peut &tre rttablie si l'on introduit une approximation suppltmentaire.Es wird gezeigt, dass die INDO-Naherung zur Roothaan'schen Theorie im allgemeinen nicht zu Ausdrucken fuhrt, die invariant unter Drehungen der lokalen atomaren Achsen sind. Wenn aber nur s-und p-Funktionen im atomaren Basissatz verwendet werden, sind die Gleichungen invariant, was mit gewissen speziellen Eigenschaften der p-Funktionen zusammenhangt. Wenn d-Orbitale angewandt werden, geht die Drehungsinvarianz verloren. Sie kann aber mittels einer zugefugten Annaherung wiederhergestellt werden.
Summary. A new INDO method is developped, in which the semi-empirical evaluation of one-center integrals is based upon the energy expression of an atom in a valence state, according to Slater, Mulliken, Hinze and Jaffe. The values of these integrals for the first and second row elements are reported. The diatomic bonding parameters were calibrated against experimental molecular valence electronic energies (VEE). The computed WE-values for a series of various aliphatic and unsaturated molecules are in fair agreement with experiment.
Received 14/4/78 -Accepted 9/5/78.for the second order correlation corrections to the molecular dipole moment obtained via a Spin Unrestricted Hartree Fock procedure. It is shown that this expression can be considerably simplified in the case of a closed-shell molecule. The final result is computationally attractive.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.