CNDO/S parametrization

Prediction of optical rotatory strengths on the basis of semiempirical electronic structure methods are generally unreliable and have not been widely employed. The principal limitation is the small size and assumed orthogonality of the basis set, which precludes accurate description of the excited state. However, the CNDO/S parametrization, without Cl, has been claimed to have some success. " In addition, CNDO/OPTIC-2, an adaptation which incorporates singles and doubles Cl, has been introduced for the calculation of transition moments and prediction of rotatory strengths. ... 

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