Ab initio effective rotational Hamiltonians - A comparative study

Patrick Cassam-Chenaï (1) , Yann Bouret (1) , Michaël Rey (2) , S. A. Tashkun (2, 3) , Andrei Nikitin (3, 2) , Vladimir G. Tyuterev (2)

1 JAD - Laboratoire Jean Alexandre Dieudonné
2 GSMA - Groupe de spectrométrie moléculaire et atmosphérique
3 LTS - Laboratory of Theoretical Spectroscopy [Tomsk]

Two independent methods to obtain ab initio effective rotational Hamiltonians have been implemented recently. The first one is based on a generalization of perturbation theory to non-commutative rings, the other one on contact transformation techniques. In principle, both methods are able to give rotational Hamiltonians including centrugal distortion effects of arbitrary high orders. These methods are compared for the first time in this article with regard to calculations of the rotational levels of methane vibrational ground state.

Mots clés: Rotational spectra; Methane; Contact transformation; generalized perturbation; effective Hamiltonian

Domaines: Chimie théorique et/ou physique; Chimie-Physique [physics.chem-ph]

Patrick Cassam-Chenaï, Yann Bouret, Michaël Rey, S. A. Tashkun, Andrei Nikitin, et al.. Ab initio effective rotational Hamiltonians - A comparative study. International Journal of Quantum Chemistry, 2012, 112 (9), pp.2201-2220. ⟨10.1002/qua.23183⟩. ⟨hal-00588499v2⟩