Semiempirical implementation of strictly localized geminals for analysis of molecular electronic structure

Approximate electronic trial wave function taken as the antisymmetrized product of strictly localized geminals (APSLG) is implemented for semiempirical analysis of molecular electronic structure of “organic” compounds and for calculations of their heats of formation. This resulted in an O(N)‐scaling method. Using the MINDO/3 form of the semiempirical Hamiltonian with reparameterized β_AB values in combination with the APSLG form of the wave function yields the computational procedure BF'98. Calculations on the heats formation and the equilibrium geometries for a wide range of molecules show that the APSLG‐MINDO/3 approach is more favorable than its self‐consistent field‐based counterpart. Also, the APSLG formalism allows to interpret molecular electronic wave function in chemically sensible terms. © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 752–764, 2001