We have developed a new form of the intermolecular potential that is consistent with ab initio structures, interaction energies, interaction forces, intermolecular force constants, and dipole derivatives of four different hydrogen-bonded structures of the formic acid dimer. The ab initio "data" are based on a scaled HF/6-311++G** force field in nonredundant coordinates and reflect a reassignment of some bands in the spectrum. The model incorporates charges, charge fluxes, atomic dipoles, and van der Waals interactions, and its successful reproduction of the intermolecular force constants indicates that it may provide a more general description of detailed features of the hydrogen bond.