Ab initio analytical potential energy surface and quasiclassical trajectory study of the O(+)((4)S)+H(2)(X (1)Sigma(g) (+))-->OH(+)(X (3)Sigma(-))+H((2)S) reaction and isotopic variants

Rodrigo Martínez; Judith Millán; Miguel Gonzalez

doi:10.1063/1.1638735

Ab initio analytical potential energy surface and quasiclassical trajectory study of the O(+)((4)S)+H(2)(X (1)Sigma(g) (+))-->OH(+)(X (3)Sigma(-))+H((2)S) reaction and isotopic variants

J Chem Phys. 2004 Mar 8;120(10):4705-14. doi: 10.1063/1.1638735.

Authors

Rodrigo Martínez¹, Judith Millán, Miguel Gonzalez

Affiliation

¹ Departamento de Quimica, Universidad de La Rioja, C/Madre de Dios, 51. 26006 Logrono, Spain.

PMID: 15267331
DOI: 10.1063/1.1638735

Abstract

An analytical potential energy surface (PES) representation of the O(+)((4)S)+H(2)(X (1)Sigma(g) (+)) system was developed by fitting around 600 CCSD(T)/cc-pVQZ ab initio points. Rate constant calculations for this reaction and its isotopic variants (D(2) and HD) were performed using the quasiclassical trajectory (QCT) method, obtaining a good agreement with experimental data. Calculations conducted to determine the cross section of the title reaction, considering collision energies (E(T)) below 0.3 eV, also led to good accord with experiments. This PES appears to be suitable for kinetics and dynamics studies. Moreover, the QCT results show that, although the hypotheses of a widely used capture model are not satisfied, the resulting expression for the cross section can be applied within a suitable E(T) interval, due to errors cancellation. This could be a general situation regarding the application of this simple model to ion-molecule processes.