Heats of atomization of conjugated hydrocarbons by a new semiempirical method

Heats of atomization of a range of conjugated hydrocarbons are calculated by a semiempirical method which combines characteristic features of the MO and the VB theory. The -ground state of each hydrocarbon is represented as a linear combination of Kekulé structures where, unlike the VB theory, each Kekulé structure is a determinant containing bond Orbitals. In this approach only the Hückel parameter has to be adjusted. Experimental heats of atomization are by this method reproduced approximately equally well as by the more sophisticated SCF-MO approach. The use of this method is however much simpler since it amounts to a single diagonalization of a matrix of the order equal to the number of Kekulé structures only.