Abstract
The extension of the CNDO/S calculation to aromatic and heterocyclic compounds containing Si, P, S or Cl was investigated in detail. Parameters of the second-row elements were optimized by using as many types of compound as possible. The spd basis sets were shown to be superior to the sp basis sets in the calculated transition energies but also orbital energies coincide very well with observed values without exception. The method presented in this work is expected to be widely applicable to the calculation of the electronic states of many aromatic and heterocyclic compounds containing second-row elements.
