AB-INITIO LOCALLY DISTRIBUTED ORIGIN GAUGE CALCULATIONS OF VIBRATIONAL CIRCULAR-DICHROISM INTENSITY - FORMULATION AND APPLICATION TO (S,S)-OXIRANE-2,3-H-2(2)

A new, locally distributed-origin gauge (LDO) model for calculating vibrational circular dichroism intensity, which requires only unperturbed, non-localized, ground-state electronic wavefunctions, is formulated. Implementation of the model at the ab initio level yields VCD intensities for (S, S)-oxirane-2,3-H-2(2) that agree well both with experiment and with earlier calculational methods requiring either a sum over excited states, wavefunctions perturbed by a magnetic field, or localized molecular orbitals. The LDO model is useful for interpretation of intense VCD features for molecules too large for current implementation of more complete a priori formalisms and for molecules with conformational flexibility that require calculations on a large number of conformers.