Semiempirical molecular orbital calculations on closed- and open-shell hydrocarbons

Abstract

The LCAO–MO–SCF (σ+π) method is shown to predict accurately ΔH_a, R_ij, and π and σ-electron densities irrespective of the value of W_pi used. The optimum value of W_pi to predict accurate ionization potentials is shown to be –9·64 eV. The theory is extended to open-shell cases, and accurately correlates with experimental electron density measurements. Thus the LCAO–MO–SCF (π+ BEEM) theory can successfully predict molecular properties dependent on both the energy and wavefunction for both open- and closed-shell systems.