Potential energy surface and bound states of the NH3–Ar and ND3–Ar complexes

Abstract

Interaction of the NO 3pπ Rydberg state with Ar: Potential energy surfaces and spectroscopy J. Chem. Phys. 138, 214313 (2013) A new, four-dimensional potential energy surface for the interaction of NH 3 and ND 3 with Ar is computed using the coupled-cluster method with single, double, and perturbative triple excitations and large basis sets. The umbrella motion of the ammonia molecule is explicitly taken into account. The bound states of both NH 3 -Ar and ND 3 -Ar are calculated on this potential for total angular momentum values from J = 0 to 10, with the inclusion of Coriolis interactions. The energies and splittings of the rovibrational levels are in excellent agreement with the extensive high-resolution spectroscopic data accumulated over the years in the infrared and microwave regions for both complexes, which demonstrates the quality of the potential energy surface. © 2014 AIP Publishing LLC.

Rotational Spectroscopy of the NH3–H2 Molecular Complex

“…Qualitatively, this picture is the same as observed and calculated for the NH 3 -Ar complex (Zwart et al 1991;Loreau et al 2014), where the inversion motion of ammonia is hardly affected in the Σ=0 states, while it is nearly quenched in the Π states. The reason that the inversion splittings are much smaller in NH 3 -(o)-H 2 than in NH 3 -(p)-H 2 is that the anisotropy of the intermolecular potential with respect to the orientation of H 2 is reflected by the interaction of NH 3 with (o)-H 2 , whereas it is largely averaged out when NH 3 interacts with (p)-H 2 .…”

“…The ground state inversion levels are split by 0.7934 cm −1 in the free monomer. Since the potential of Maret et al (2009) does not depend on the umbrella inversion coordinate, we used a two-state model tested in previous work on NH 3 -He (Gubbels et al 2012) and NH 3 -Ar (Loreau et al 2014). It is assumed in this model that the NH 3 molecule tunnels between two structures, umbrella up and umbrella down, with an umbrella angle given by the equilibrium value in free ammonia.…”

Scattering of NH3 and ND3 with rare gas atoms at low collision energy

“…1 in Ref. 33 for an illustration of the coordinate system). For θ ′ = 0 or π, the complex has orientation Rg-NH 3 or Rg-H 3 N, respectively.…”

“…The N-H bond r length was fixed at its vibrationally averaged value, r 0 = 1.9204 a 0 , as calculated in Ref. 33.…”

“…PESs for the interaction of NH 3 with helium 25 and argon 33 that include a dependence on the inversion coordinate of NH 3 have recently been reported. While a few ab initio studies have been performed on the interaction of ammonia with the other rare gases, 16,18,32,34,35 they did not include a description of the long-range potential that is required for low-energy scattering.…”