By using the potential energy surface of Strey and Mills and the kinetic energy operator expressed in terms of valence coordinates, rewritten in order to calculate analytically the angular part of the Hamiltonian matrix elements, the low-lying vibrational levels of the acetylene-like molecules are derived variationally.
Belafhal, A., Nauts, A., & Chapuisat, X. (2012). Vibrational spectra of the acetylene-like molecules by using the potential energy surface of strey and mills. Physical & Chemical News, 65, 43-49. https://hdl.handle.net/2078.5/47262 (Original work published 2012)