  Methyl benzoate (MB) is studied as a model compound for the development of
new IR pulse schemes with possible applicability to biomolecules. Anharmonic
vibrational modes of MB are calculated on different level (MP2, SCS, CCSD(T)
with varying basis sets) ab-initio PESs using the vibrational self-consistent
field (VSCF) method and its correlation corrected extensions. Dual level
schemes, combining different quantum chemical methods for diagonal and coupling
potentials, are systematically studied and applied successfully to reduce the
computational cost. Isotopic substitution of {\beta}-hydrogen by deuterium is
studied to obtain a better understanding of the molecular vibrational coupling
topology.
