Accurate Potential Energy Surface for Quartet State HN2 and Interplay of N(4S) + NH(X̃3Σ-) versus H + N2(A3Σu+) Reactions

V C Mota; B R L Galvão; D V B Coura; A J C Varandas

doi:10.1021/acs.jpca.9b09467

Accurate Potential Energy Surface for Quartet State HN₂ and Interplay of N(⁴S) + NH(X̃³Σ^-) versus H + N₂(A³Σ_u⁺) Reactions

J Phys Chem A. 2020 Feb 6;124(5):781-789. doi: 10.1021/acs.jpca.9b09467. Epub 2020 Jan 28.

Authors

V C Mota¹, B R L Galvão², D V B Coura¹, A J C Varandas^{3

4}

Affiliations

¹ Departamento de Fı́sica , Universidade Federal do Espı́rito Santo , 29075-910 Vitória , Brazil.
² Departamento de Quı́mica , Centro Federal de Educação Tecnológica de Minas Gerais, CEFET-MG , Av. Amazonas 5253 , 30421-169 Belo Horizonte , Minas Gerais , Brazil.
³ School of Physics and Physical Engineering , Qufu Normal University , 273165 Qufu , China.
⁴ Coimbra Chemistry Center and Chemistry Department , University of Coimbra , 3004-535 Coimbra , Portugal.

PMID: 31922752
DOI: 10.1021/acs.jpca.9b09467

Abstract

A global potential energy surface for the lowest quartet state of HN₂ is reported for the first time from accurate multireference ab initio calculations extrapolated to the complete basis set limit using the double many-body expansion method. All its stationary points are characterized, with the lowest quartet of HN₂ predicted to have a bent global minimum 36 kcal mol^-1 below the N(⁴S) + NH(X̃³Σ^-) asymptote, from which it is barrierlessly achievable. The entire set of calculated ab initio points has been fitted for energies up to 1000 kcal mol^-1 above the global minimum with an RMSD of 0.89 kcal mol^-1, a gap comprising all identified stationary points. Special care is taken in modeling the involved long-range forces and cusps caused by crossing seams. The novel PES prompts for the calculation of rate constants for several unexplored reactions that are relevant for combustion, plasma, and atmospheric chemistry.