Semiempirical implementation of the APSLG approach

A method using a trial wave function in the form of the antisymmetrized pro duct of strictly localized geminals (APSLG) is developed at the semiempiric al level. The Hamiltonian is taken in the MINDO/3 form but with resonance p arameters slightly reparametrized. The equilibrium geometries and heats of formation of a series of organic compounds are calculated by the APSLG-MIND O/3 method and compared with the experimental data and the results of SCF-M INDO/3 calculations. Two different schemes of calculation of the ionization potentials are developed and thoroughly tested. The O(N)-scalability and a cceptable accuracy are proved for the proposed APSLG-MINDO/3 method.