Intermediate Neglect of Differential Overlap. A semiempirical method of quantum chemistry [ POPLE, BEVERIDGE, and DOBOSH (1967)].
(Intermediate Neglect of Differential Overlap) A semiempirical method closely related to the CNDO method, where all terms of the Fock matrix used in CNDO are included, but the restriction that the monocentric two-electron integrals all be equal is lifted.
INDO stands for Intermediate Neglect of Differential Overlap. It is a development of CNDO/2 introduced by John Pople. Like CNDO/2 is uses zero-differential overlap for the two-electron integrals but not for integrals that are over orbitals centred on the same atom.