A theoretical treatment of the intersystem crossing in the spin-forbidden reaction [formula omitted

Abstract

The mechanism of the spin-forbidden reaction NO(X 2Π)+CO(X 1Σ +) → N( 4S)+CO 2(X 1Σ + g) is considered. Two minimum energy points on the doublet–quartet crossing surface are reported using multireference configuration interaction (MRCI) wavefunctions. The lowest-energy crossing point has an approximate C 2v structure resembling the products N+CO 2. This region lies 60 kcal/mol above the reactant channel, suggesting that the title reaction would not occur under typical combustion conditions. A higher-energy point with a linear structure is also located. Two local minima on the lowest 2 A″ potential energy surface are reported at the QCISD and MRCI levels.