Semiempirical SINDO

A semiempirical method with a similar acronym, SINDO, but with completely different features has been developed by Golebiewski at el. [66],... 

Recognizing the importance of orthogonalization effects (see Section 2.38.2.6), which are neglected in many semiempirical SCF MO methods, INDO-based methods with orthogonalization corrections, SINDO, SINDO1 and MSINDO, " have been developed. The orthogonalization models... 

Semiempirical SCF calculations were done using the approximations NDDO (neglect of diatomic differential overlap) [18], MNDO (modified neglect of diatomic overlap) [19], INDO (intermediate neglect of differential overlap) [20], SINDO (symmetrically orthogonalized INDO [21]) [22], and CNDO (complete neglect of differential overlap) [20, 23]. Another type of approximation [24] to the ab initio method was also applied to OF2 [16]. 

Orbital energies from other ab initio calculations pertain to assumed bond lengths [9] or to the experimental geometry [13, 14]. Orbital energies were also calculated semiempirically by the extended Hiickel method [11], by CNDO [15], INDO [15, 16], MNDO [17], and SINDO [18] (symmetrically orthogonalized INDO, see [19]). 

Semiempirical methods followed a different path. Instead of trying to solve the integrals, they are replaced by approximations. This resulted in the development of many closely related yet distinct methods, the more popular of which were CNDO, INDO, methods MINDO/3 " and SINDO," the NDDO methods, and ZINDO. All the.se methods use a common approximation, that is, all two-electron three- and four-center integrals are set to zero. Because there are differences... 

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