The requirements of an electrostatic model of the intermonomer interactions needed to reproduce the C=O stretch mode splitting, Delta v(C=O), in the formic acid dimer have been reexamined in the light of their also being consistent with intermonomer Coulomb and van der Waals energies. The experimental value of Delta v(C=O) has been reevaluated and is determined to be 71 cm(-1). A complete cubic and quartic ab initio anharmonicity correction is found to be 9 cm(-1). The remaining harmonic component of Delta v(C=O) can only be reconciled with the ab initio intermonomer Coulomb energy and the nonnegligible van der Waals energy if atomic dipoles are added to the charges and the charge fluxes of the electrostatic model.