Calculation of Optical Rotational Strength by Means of Various Types of Molecular Orbitals

Abstract
The optical rotational strengths of the methyl derivatives of cyclohexanone were calculated by means of various types of molecular orbitals, which were converted from those used in the CNDO/2 method. One of them is represented as a Sla ter-basis atomic orbital transformed from molecular orbitals on a CNDO basis by using the overlap matrix. Another was obtained only by modifying the normalization coefficient of the molecular orbitals. From the results, the two-center matrix elements in the calculation of rotational strengths was found to be not negligible, hence, the above-mentioned transformation was indicated to be indispensable. Good agreement with the experimental results was found for the transformed molecular orbitals, especially for those with a modification of the normalization coefficient. The theoretical grounds for these transformations are discussed. The formulae for the matrix elements of the gradient operator which are necessary for the calculation of the rotational strength are given in the appendix.