title: A new ab initio potential energy surface for the collisional excitation of HCN by para- and ortho-H2.
abstract: We present a new four-dimensional potential energy surface for the collisional excitation of HCN by H2. Ab initio calculations of the HCN-H2 van der Waals complex, considering both molecules as rigid rotors, were carried out at the explicitly correlated coupled cluster with single, double, and perturbative triple excitations [CCSD(T)-F12a] level of theory using an augmented correlation-consistent triple zeta (aVTZ) basis set. The equilibrium structure is linear HCN-H2 with the nitrogen pointing towards H2 at an intermolecular separation of 7.20 a0. The corresponding well depth is -195.20 cm(-1). A secondary minimum of -183.59 cm(-1) was found for a T-shape configuration with the H of HCN pointing to the center of mass of H2. We also determine the rovibrational energy levels of the HCN-para-H2 and HCN-ortho-H2 complexes. The calculated dissociation energies for the para and ortho complexes are 37.79 cm(-1) and 60.26 cm(-1), respectively. The calculated ro-vibrational transitions in the HCN-H2 complex are found to agree by more than 0.5% with the available experimental data, confirming the accuracy of the potential energy surface.
authors: Université de Bordeaux, ISM, CNRS UMR 5255, 33405 Talence Cedex, France.
authors: Otoniel
authors: O
authors: Denis-Alpizar
authors: LOMC - UMR 6294, CNRS-Université du Havre, 25 rue Philippe Lebon, BP 540, 76058, Le Havre, France.
authors: Yulia
authors: Y
authors: Kalugina
authors: Université de Bordeaux, ISM, CNRS UMR 5255, 33405 Talence Cedex, France.
authors: Thierry
authors: T
authors: Stoecklin
authors: LOMC - UMR 6294, CNRS-Université du Havre, 25 rue Philippe Lebon, BP 540, 76058, Le Havre, France.
authors: Mario Hernández
authors: MH
authors: Vera
authors: Departamento de Física, Universidad de Matanzas, Matanzas 40100, Cuba.
authors: François
authors: F
authors: Lique