Ab initio calculations on the effect of different basis sets and electron correlation on the transition state for the reactions HNC ⇌ HCN and BCN ⇌ BNC

The geometry of the ground states of the isomers and transition state for the systems HCN ? HNC and BCN ? BNC have been investigated using a wide variety of basis sets, both at the self-consistent-field (SCF ) level and including correlation at the second-, and third-order Møller–Plesset (MP 2 and MP 3) levels. The barrier to isomerization and the isomerization energy were shown to be strongly dependent on the basis set and method, particularly for the BCN system.