  The ground-state energy and density of four low-energy conformations of the
formic acid dimer were calculated via Partition Density Functional Theory
(PDFT). The differences between isolated and PDFT monomer densities display
similar deformation patterns for primary and secondary hydrogen bonds among all
four dimers. In contrast, the partition potential shows no transferable
features in the bonding regions. These observations highlight the global
character of the partition potential and the cooperative effect that occurs
when a dimer is bound via more than one hydrogen bond. We also provide
numerical confirmation of the intuitive (but unproven) observation that
fragment deformation energies are larger for systems with larger binding
energies.
