Ab initio ground potential energy surface ((3)A(')) for the O(P-3)+N2O reaction and kinetics study

An ab initio CASPT2//CASSCF study of the (3)A(') ground potential energy su rface for the O(P-3)+N2O(X (1)Sigma (+)) reaction has been performed, inves tigating the two predominant reactive channels. Symmetry breaking is report ed for some of the structures. Rate constants are calculated by means of th e transition state theory yielding values in almost quantitative agreement with experiment for the 2 NO(X (2)Pi) channel, but at variance with experim ent for the N-2(X (1)Sigma (+)(g))+O-2(X (3)Sigma (-)(g)) one. A preliminar y study on the possible existence of surface crossings ((3)A(')-(1)A('), (3 )A(")-(1)A("), and (3)A"-(3)A(') intersections) reveals that more efforts a re warranted to fully explain the origin of this discrepancy. (C) 2001 Amer ican Institute of Physics.