Anharmonic potential function and rotation-inversion energy levels of H 3O +

Abstract

An analytic anharmonic potential function for H 3O + is determined by fitting to experimental and ab initio calculated data using the nonrigid invertor Hamiltonian method [V. S̆pirko, J. Mol. Spectrosc. 101, 30–47 (1983)]. Using this potential function, lower inversion and vibration states of H 3O + and D 3O + are obtained in close agreement with the corresponding experimental data and predictions can be made of some transitions to excited states which have not been observed so far in the laboratory, particularly the forbidden transitions in H 3O +.