4 research outputs found
Ab Initio MBPT(4) Calculations of the Inversion Potential Function of NH3
The inversion potential function and the dominant (in-plane)
and inversion-(in-plane) force constants are calculated by means
of the fourth-order many-body perturbation theory in the extended
double-zeta-plus polarization basis set. Using the ab initio potential
surfaces and the non-rigid invertor Hamiltonian the inversion
energy levels of 14NH3 are calculated. Despite the significant residual
error in the perturbation expansion, the results indicate that
the full fourth order procedure may be considered as a reliable
tool for studying vibrational anharmonicity in other non-rigid
molecules