The theoretical deformation density for oxalic acid

Theoretical deformation densities for oxalic acid and oxalic acid dihydrate have been determined by ab initio Hartree-Fock calculations using extended atomic basis sets. The results are in good agreement with experimental X-N maps. The non-sphericity of the deformation density in certain bond cross sections has been established. Special emphasis is placed on the discussion of lone pairs and hydrogen bonds. The deformation density for the hydrate water has been analyzed.