Coupled-Cluster and Many-Body Perturbation Study of Energies, Structures, and Phonon Dispersions of Solid Hydrogen Fluoride

A linear-scaling electron-correlation method based on a truncated many-body expansion of the energies of molecular crystals has been applied to solid hydrogen fluoride. The energies, structures, harmonic, and anharmonic frequencies of the infrared- and/or Raman-active vibrations, phonon dispersions, and inelastic neutron scattering (INS) of the solid have been simulated employing an infinite, periodic, one-dimensional zigzag hydrogen-bonded chain model. The Hartree-Fock, second-order Moller-Plesset (MP2), coupled-cluster singles and doubles (CCSD), and CCSD with a noniterative triples correction [CCSD(T)] methods have been combined with the aug-cc-pVDZ and aug-cc-pVTZ basis sets and, in some instances, the counterpoise corrections of the basis-set superposition errors. The computed structural parameters agree with the observed within 0.1-0.2 angstrom and a few degrees, and the anharmonic frequencies obtained by vibrational MP2 allowing two-phonon couplings reproduce the observed frequencies semiquantitatively if the potential energy surface is obtained by a correlated theory. They support the revised infrared and Raman band assignments of librational modes made by Hirata and Iwata (J.Phys Chem A 1998, 102, 8426) and provide more detailed assignments of the observed INS features. (c) 2009 Wiley Periodicals, Inc. Int J Quantum Chem 109: 1928-1939, 2009