Extending the vibrational self-consistent method: Using a partially separable wave function for calculating anharmonic vibrational states of polyatomic molecules

The vibrational self-consistent-field (VSCF) method was extended using a partially separable wave function for the calculation of anharmonic vibrational states of polyatomic molecules. The method analyzed the correlation effects between modes in VSCF calculations in which some modes were treated as mutually fully correlated and some as separable. The explicitly coupled modes were chosen on the physical ground.