Anharmonic force constants of acetylene. Cubic and quartic force constants of acetylene; calculations with a general quartic force field and an empirical anharmonic potential function

Abstract

Abstract Literature values of the vibrational frequencies and rotational constants of acetylene, acetylene-d1 and acetylene-d2 have been used to determine the anharmonic force constants. The most general quartio valence potential function has been investigated although there are presently insufficient data to fix all the force constants uniquely. An empirical 19-parameter anharmonic potential function is described which fits the experimental data as well as the 40-parameter general force field. Internally self-consistent sets of xXXX' and ωs are given.