BASIS-SET CONVERGENCE AND CORRELATION-EFFECTS IN VIBRATIONAL CIRCULAR-DICHROISM CALCULATIONS USING LONDON ATOMIC ORBITALS

Using London atomic orbitals (LAO) the vibrational dipole and rotatory strengths are derived for the natural connection of molecular orbital s. The resulting expressions are significantly simpler than the previo us ones obtained for the symmetric connections. Single configurational self-consistent field (SCF) calculations of vibrational dipole streng ths and LAO vibrational rotatory strengths are carried out for five sm all and medium sized chiral molecules using various basis sets. These calculations show similar basis set convergence for the vibrational di pole strengths and the vibrational rotatory strengths. The vibrational rotatory strengths for trans[2,3-H-2(2)]oxirane from a multiconfigura tional (MC)-SCF wavefunction expanded in 30039 determinants give an im proved agreement with the experimental spectrum compared with the rota tory strengths from the SCF wavefunction. The agreement of the MCSCF s pectrum is comparable to those of previous MP2 spectra.