Methods CS-INDO

The results of the above cited applications [18-28,45] have clearly shown that CS INDO method is fairly successful in combining equally satisfactory predictions of electronic spectra and potential surfaces (especially along internal rotation pathways) of conjugated molecules, a goal never reached by other NDO-type procedures. CS INDO shares, at least partly, the interpretative advantages of the CIPSI-PCILO-CNDO procedure [32,33,36,37], coming from using the same hybrid AO basis sets, but improves its predictive capabilities as far as spectroscopic and photochemical properties are concerned. 

A double perturbation expansion of the FC coupling term up to second order in both the magnetic and Coulomb residual interactions was carried out within the CS-INDO method in polymethyne chains. It should be noted, however, that such an expansion usually converges only slowly and, in order for the SOS approach to be equivalent to the FPT and CHF ones, some of the terms in it must be summed to infinite order with respect to the Coulomb interaction. The authors conclude that their calculations do not succeed in generating unique effective parameters 5 (0) and fo " example,... 

Baraldi, L Momicchioli, F. Ponterini. G. Vanossi. D. Solvent effects within the CS INDO method. Geometrical distortion and solvatochromism of merocyanine dyes. Chem. Phys. 1998, 238, 353-364. 

Calculations on MDA with semiempirical methods (INDO and CNDO/2) for C2v and Q conformers gave almost coincidental potential wells whereas STO-3 G shows the c2v to have a single minimum but of higher energy than Cs by 44.5 kJ mol-1 (6-31G basis set)109). 

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