A potential function model containing distributed repulsion, dispersion, and electrostatic interactions is applied to hydrogen halide dimers and carbon dioxide-hydrogen halide complexes. The (HX)(2) functions are compatible with all experimental data and are compared with both empirical and large scale ab initio potential surfaces. The main focus of this paper is the CO2-HX group. We obtain excellent results for CO2-HF and CO2-HCl, describing essentially linear molecules undergoing large amplitude vibrations that closely resemble rigid bender behavior. The calculated CO2-HBr equilibrium structure is not in agreement with vibrationally averaged experimental results. This may arise from vibrational averaging effects. It is shown that different views of the same potential function can give very different impressions of structure and internal motions.