The barrier to inversion of ammonia

• Published in: Chemical physics letters Vol. 370; no. 3; pp. 360 - 365
• Main Authors: Léonard, Céline, Carter, Stuart, Handy, Nicholas C
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 14.03.2003; Elsevier Science; Elsevier
• Subjects: Atomic and molecular physics; Barrier heights (internal rotation, inversion, rotational isomerism, conformational dynamics); Chemical Sciences; Exact sciences and technology; Molecular properties and interactions with photons; or physical chemistry; Physics; Properties of molecules and molecular ions; Theoretical and; Configuration inversion; Polyatomic molecules; Ammonia; Inorganic compounds; Inversion barrier; Vibrational energy level; Theoretical study
• ISSN: 0009-2614; 1873-4448
• DOI: 10.1016/S0009-2614(03)00107-6

A six-dimensional analytic potential energy surface for NH 3 has been obtained using ab initio CCSD(T) data. The variational method has been used to determine its vibrational energy levels. The parameters in the surface which describe inversion have been refined such that the vibrational levels for inversion give best agreement with observation. Nearly all the fundamentals and overtones of the refined surface then agree with observation to within 1 cm −1. The barrier to inversion is found to be 1769 cm −1. This is compared with other computed estimates of 1766 and 1777 cm −1 which appear in the literature.