REKS calculations on ortho-, meta- and para-benzyne

Abstract

Spin-restricted ensemble-referenced Kohn–Sham (REKS) calculations have been performed on isomeric benzyne systems. The density functional results compare favorably with those of multi-reference CASPT2 and CASRS3 methods. In general for enthalpies of isodesmic reactions, the REKS energies are in better agreement with experiment compared with the ab initio calculations. Experimental singlet–triplet energy gaps are reproduced to within 1 kcal mol⁻¹ of experimental values.