Ab initio studies on hydrogen-bonded clusters: Structure and vibrational spectra of cyclic (HF)n complexes

Equilibrium structures of cyclic (HF)n clusters with n = 3, 4, and 6, and vibrational spectra of cyclic (HF)3 and (HF)4 were investigated with the aid of ab initio methods including electron correlation at a size-extensive level. Computed ground state properties such as equilibrium structures, stabilization energies, harmonic vibrational frequencies, and infrared intensities are compared with the corresponding quantities of HF monomer and dimer. Trends in the modifications of monomer properties as induced by cluster formation are monitored. Results for the structure and energetics of cyclic Dnh transition states of (HF)n with n = 2, 3, 4, and 6 are also reported.