High-accuracy DMBE potential energy surface for CNO(A''4) and the rate coefficients for the C + NO reaction in the A'2, A''2, and A''4 states

Márcio O Alves; Vinícius C Mota; João P Braga; António J C Varandas; Hua Guo; Breno R L Galvão

doi:10.1063/5.0180918

High-accuracy DMBE potential energy surface for CNO(A''4) and the rate coefficients for the C + NO reaction in the A'2, A''2, and A''4 states

J Chem Phys. 2023 Dec 7;159(21):214307. doi: 10.1063/5.0180918.

Authors

Márcio O Alves¹, Vinícius C Mota², João P Braga³, António J C Varandas^{2

4

5}, Hua Guo^{6

7}, Breno R L Galvão^{1

6

7}

Affiliations

¹ Centro Federal de Educação Tecnológica de Minas Gerais, CEFET-MG, Av. Amazonas 5253, 30421-169 Belo Horizonte, Minas Gerais, Brazil.
² Departamento de Física, Universidade Federal do Espírito Santo, 29075-910 Vitória, Brazil.
³ Departamento de Química, Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, Brazil.
⁴ School of Physics and Physical Engineering, Qufu Normal University, Qufu 273165, People's Republic of China.
⁵ Coimbra Chemistry Centre and Chemistry Department, University of Coimbra, 3004-535 Coimbra, Portugal.
⁶ Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA.
⁷ Center for Computational Chemistry, University of New Mexico, Albuquerque, New Mexico 87131, USA.

PMID: 38054514
DOI: 10.1063/5.0180918

Abstract

An accurate potential energy surface (PES) for the lowest lying A''4 state of the CNO system is presented based on explicitly correlated multi-reference configuration interaction calculations with quadruple zeta basis set (MRCI-F12/cc-pVQZ-F12). The ab initio energies are fitted using the double many-body expansion method, thus incorporating long-range energy terms that can accurately describe the electrostatic and dispersion interactions with physically motivated decaying functions. Together with the previously fitted lowest A'2 and A''2 states using the same theoretical framework, this constitutes a new set of PESs that are suitable to predict rate coefficients for all atom-diatom reactions of the CNO system. We use this set of PESs to calculate thermal rate coefficients for the C(P3) + NO(Π2) reaction and compare the temperature dependence and product branching ratios with experimental results. The comparison between theory and experiment is shown to be improved over previous theoretical studies. We highlight the importance of the long-range interactions for low-temperature rate coefficients.