We develop a simple semiempirical Pariser-Parr-Pople-type model of a metal. It can be used for studies of adsorption and of the interactions between the metal surface and external charges, and is compatible with ab initio description of the molecules outside the metal. We investigate the dependence of the image-type field on the few parameters that control the model behavior, and develop a simple direct minimization self-consistent field technique that is useful for convergence in nearly degenerate cases. (C) 2001 American Institute of Physics.