Variable ζ calculation for self-consistent screening parameters in ab initio molecular theory

A resolution of Roothaan's HF–SCF–LCAO–MO equations is proposed in which atomic orbital exponents (ζ) are made dependent on the molecular charge distribution and included in the self-consistent scheme. Screening parameters so obtained are self-consistent with the molecular orbital coefficients and compare closely to optimum orbital exponents found by other methods. The technique is applied to the ground, lowest positive, and lowest negative ion states of the hydride series LiH, BH, and HF. Calculated potential curves are used to define purely theoretical values for the vertical and adiabatic ionization energies and electron affinities. Predictions are compared to experimental values where available.