THEORETICAL-STUDY OF THE CIRCULAR-DICHROISM AND VUV SPECTRA OF TRANS-2,3-DIMETHYLOXIRANE

Ab initio configuration interaction calculations with various molecular orbital basis sets have been carried out for the first states of each type (X(1)A, ten n(b)-->Ryd, n(b)-->sigma*, four sigma-->Ryd, sigma-->sigma*) of trans-2,3-dimethyloxirane in order to elucidate its circular dichroism and VUV spectra. Particular attention was placed on finding the energetic location of the first valence states. Localized molecular orbitals based on the B-2 cation are found to give the best agreement and allow for definite assignment of the spectra up to approximate to 8.5 eV. The CD signals (rotatory strengths) of dimethyloxirane could also be explained based on its electronic structure.