A high level theoretical investigation of the cyclic hydrogen fluoride trimer

A high level ab initio theoretical investigation of the cyclic hydrogen fluoride trimer was carried out. The structures of the hydrogen fluoride monomer, dimer, and trimer were fully optimized at the coupled-cluster level of theory including single, double, and perturbatively applied connected triple excitations [CCSD(T)] using three large basis sets. Geometrical parameters, dipole moments, harmonic vibrational frequencies, infrared intensities, and total energies are reported for each equilibrium structure. Changes in bond lengths and shifts in HF stretching frequencies relative to the monomer, as well as the dissociation energies corresponding to various fragmentation pathways, are given for the dimer, trimer, and their deuterated isotopomers. The theoretical results presented here are compared to the available experimental data and to those obtained from empirically refined potential energy surfaces.