SINDO symmetrically orthogonalized

SINDO symmetrically orthogonalized intermediate neglect of differential overlap... 

CNDO/S, CNDO/FK, CNDO/BW, INDO/1, INDO/2, INDO/S and SINDOl. These methods are rarely used in modem computational chemistry, mainly because the modified methods described below usually perform better. Exceptions are INDO based methods, such as SlNDOl and INDO/S. SINDO Symmetric orthogonalized INDO) employes the INDO approximations described above, but not the ZDO approximation for the overlap matrix. The INDO/S method (INDO parameterized for Spectmscopy) is especially designed for calculating electronic spectra of large molecules or systems involving heavy atoms. 

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]). 

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