Intermediate Neglect of Differential Overlap Approximation INDO

The Intermediate Neglect of Differential Overlap (INDO) approximation neglects all two-centre two-electron integrals that are not of the Coulomb type, in addition to those neglected by the NDDO approximations. Furthermore, in order to preserve rotational invariance, i.e. the total energy should be independent of a rotation of the coordinate system, integrals such as <mA|Va|mA) and (mAvb|mAvb) must be made independent of the orbital type (i.e. an integral involving a p-orbital must be the same as with an s-orbital). This has as a consequence that one-electron integrals involving two different functions on the same atom and a Va operator from another atom disappear. The INDO method involves the following additional approximations, beside those for NDDO. One-electron integrals (eq. (3.83)):

0 0

Post a comment