Rate constants for rotational excitation of ortho- and para-NH3 colliding with 4He on an Ab initio potential energy surface

Pressure broadening and cross relaxation of ammonia perturbed by hydrogen and helium: Implications on intermolecular potentials and discussion of rotational effects

“…6. With this potential energy surface, it was possible to obtain a considerable improvement in the agreement with experimental double resonance measurements by Oka.…”

H2-Broadening Coefficients in the ν4 Band of NH3

“…On the theoretical side, a semiclassical coupled state method has been performed by Billing et al (9)(10)(11) and extended by Broquier et al (8) to derive NH 3 -He and NH 3 -H 2 pressure broadening cross sections. For the NH 3 -H 2 system at 300 K the theoretical results are in good agreement with the roughly constant cross sections measured at relatively low resolution (0.030 cm −1 ) by Aroui et al (2) in the vibrational ground state.…”

A b i n i t i o potential energy surfaces of Ar–NH3 for different NH3 umbrella angles

“…13 However, only a full potential surface enables us to calculate these observable properties, i.e., the interaction energy must be expressed as a function of coordinates that describe every possible geometry of the dimer. In this paper four complete potential energy surfaces of A r-N H 3 will be presented for four different umbrella angles of ammonia, allowing us to study the coupling between the van der Waals modes with the inversion motion of N H 3.…”