The performance of RI-MP2 based potential energy surfaces in a vibrational self-consistent field treatment

MP2 energy evaluations required for the potential energy surface underlying a perturbation theory corrected vibrational self-consistent field (PT2-VSCF) calculation may be safely approximated with the RI-MP2 method. The wavenumbers of the 32 probed open- and closed shell systems differ on average from their MP2 references by 0.0 ± 0.1 cm−1. An up to 70 fold decrease in CPU time compared to standard MP2 calculations was observed while the overall energy surface scan underlying a PT2-VSCF calculation is sped up by a factor of two. Limitations of the approach are discussed and a comparison with B3LYP based PT2-VSCF calculations is made.