Knowledge Bank

“Using a single Slater determinant and neglecting differential overlap, wave functions for HF and $HF+$ have been obtained by minimizing energy with respect to two linear coefficients and three orbital exponents. The $\pi$ ionization potential of HF computed using Koopmans’ theorem is 8.8 e.v. higher than that. obtained as the difference between best HF and best $HF+$ energies. This latter ionization potential of 14.0 e.v. may be compared with experimental values of 12.6-15.8 e.v.”