Comment on: Structures, stabilities, and intermolecular vibrational frequencies of small ammonia complexes by molecular mechanics for clusters analysis

Abstract
We calculate binding energies for the molecular mechanics for clusters (MMC) geometries obtained by Dykstra and Andrews [J. Chem. Phys. 92, 6043 (1990)] for neutral ammonia clusters and compare these energies with those obtained from previous calculations by Sagarik, Ahlrichs, and Brode [Mol. Phys. 57, 1247 (1986)] and Greer, Ahlrichs, and Hertel [Chem. Phys. 133, 191 (1989)]. All geometries are compared energetically near the Hartree–Fock limit; for the dimer, correlation effects are included by means of the coupled pair functional (CPF) method.