Ammonia quantum tunneling in cold rare-gas He and Ar clusters and factorial design approach for methodology evaluation.

Autor: Porto CM; Institute of Chemistry, Campinas State University, Campinas, 13083-861, São Paulo, Brazil., Barros GA; Institute of Chemistry, Campinas State University, Campinas, 13083-861, São Paulo, Brazil., Santana LC; Institute of Chemistry, Campinas State University, Campinas, 13083-861, São Paulo, Brazil., Moralles AC; Institute of Chemistry, Campinas State University, Campinas, 13083-861, São Paulo, Brazil., Morgon NH; Institute of Chemistry, Campinas State University, Campinas, 13083-861, São Paulo, Brazil. nhmorgon@unicamp.br.
Jazyk: angličtina
Zdroj: Journal of molecular modeling [J Mol Model] 2022 Sep 05; Vol. 28 (10), pp. 293. Date of Electronic Publication: 2022 Sep 05.
DOI: 10.1007/s00894-022-05267-9
Abstrakt: Quantum tunneling of the ammonia inversion motion and energy level splittings in He and Ar clusters were investigated. It was found that the double well potential (DWP) in He clusters is symmetrical and that the first layer of He atoms is able to model the system. The calculated tunneling splitting was in good agreement with the experimental, 36.4 and 24.6 cm[Formula: see text] respectively. For NH[Formula: see text] in Ar clusters, the DWP becomes slightly asymmetric, which is enough to decrease the resonance and make the symmetric DWP unable to model the system. An asymmetric potential was used and the result was in excellent agreement with the experimental splitting, of 9.0 and 10.6 cm[Formula: see text] respectively. Non-covalent interactions revealed that the asymmetry is caused by dissimilar interactions in each minimum of the double well potential. The effects of different methodologies were analyzed via a design of experiments approach. For the gas-phase NH[Formula: see text] molecule, only diffuse functions were statistically significant while for the NH[Formula: see text] embedded in He cluster both the MP2 method and polarization functions were significant. This tendency suggests higher order polarization functions may be essential to generate accurate barrier heights.
(© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)
Databáze: MEDLINE
Externí odkaz: