title: A new ab initio potential energy surface for the collisional excitation of N2H(+) by H2.
abstract: We compute a new potential energy surface (PES) for the study of the inelastic collisions between N2H(+) and H2 molecules. A preliminary study of the reactivity of N2H(+) with H2 shows that neglecting reactive channels in collisional excitation studies is certainly valid at low temperatures. The four dimensional (4D) N2H(+)-H2 PES is obtained from electronic structure calculations using the coupled cluster with single, double, and perturbative triple excitation level of theory. The atoms are described by the augmented correlation consistent triple zeta basis set. Both molecules were treated as rigid rotors. The potential energy surface exhibits a well depth of ≃2530 cm(-1). Considering this very deep well, it appears that converged scattering calculations that take into account the rotational structure of both N2H(+) and H2 should be very difficult to carry out. To overcome this difficulty, the "adiabatic-hindered-rotor" treatment, which allows para-H2(j = 0) to be treated as if it were spherical, was used in order to reduce the scattering calculations to a 2D problem. The validity of this approach is checked and we find that cross sections and rate coefficients computed from the adiabatic reduced surface are in very good agreement with the full 4D calculations.
authors.affiliation: LERMA, Observatoire de Paris, Sorbonne Université, UPMC Univ Paris 06, CNRS-UMR 8112, F-92195 Meudon, France.
authors.forename: Annie
authors.initials: A
authors.lastname: Spielfiedel
authors.affiliation: Departamento de Química y Física Teóricas, IEM-CSIC, Serrano 121, Madrid 28006, Spain.
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Senent
authors.affiliation: LOMC-UMR 6294, CNRS-Université du Havre, 25 rue Philippe Lebon, BP 1123, 76063 Le Havre, France.
authors.forename: Yulia
authors.initials: Y
authors.lastname: Kalugina
authors.affiliation: LUPM-UMR 5299, CNRS-Université de Montpellier, Place Eugene Bataillon, 34095 Montpellier Cedex, France.
authors.forename: Yohann
authors.initials: Y
authors.lastname: Scribano
authors.affiliation: LERMA, Observatoire de Paris, Sorbonne Université, UPMC Univ Paris 06, CNRS-UMR 8112, F-92195 Meudon, France.
authors.forename: Christian
authors.initials: C
authors.lastname: Balança
authors.affiliation: LERMA, Observatoire de Paris, Sorbonne Université, UPMC Univ Paris 06, CNRS-UMR 8112, F-92195 Meudon, France.
authors.forename: François
authors.initials: F
authors.lastname: Lique
authors.affiliation: LERMA, Observatoire de Paris, Sorbonne Université, UPMC Univ Paris 06, CNRS-UMR 8112, F-92195 Meudon, France.
authors.forename: Nicole
authors.initials: N
authors.lastname: Feautrier