Selected Aspects Concerning the Efficient Calculation of Vibrational Spectra beyond the Harmonic Approximation

This feature article discusses some selected aspects in the field of vibrational structure calculations based on vibrational self-consistent field, VSCF, and vibrational configuration interaction, VCI, theory. As the quality of such calculations depends strongly on the accuracy of the underlying multidimensional potential energy surface, PES, some techniques will be discussed to establish high-quality PESs in a fully automated manner. As an alternative to VCI theory multiconfiguration self-consistent field, VMCSCF, theory and in particular specific aspects concerning the integral evaluation relevant to both approaches will also be presented. Further aspects concern the efficient calculation of infrared intensities and Franck-Condon factors in vibronic transitions.(doi: 10.5562/cca2149)