CONSTRUCTION OF BASIS-SETS OF HYBRID ATOMIC ORBITALS FOR DESCRIBING THE NONEQUIVALENT BONDS OF AN ATOM WITH 3 NEIGHBORING ATOMS (SP(2) AND SP(3) HYBRIDIZATION)

The paper describes methods for obtaining basis sets of sp(2) and sp(3 ) hybrid atomic orbitals to describe nonequivalent chemical bonds in o rganic molecules with heteroatoms. Being affine, these basis sets pres ent an alternative to the conventional basis sets of Cartesian atomic orbitals. Unlike the latter, the hybrid atomic orbitals are invariant to spatial rotations of molecules, thus providing the rotational invar iance of the results of any semiempirical quantum chemical calculation s. The construction of the basis sets of hybrid functions for atoms su rrounded with three neighboring atoms (planar and nonplanar configurat ions) is considered in detail.