MODELING PROPERTIES OF THE HF DIMER IN ARGON CLUSTERS

摘要

We compare geometry configurations, vibrational properties, and electronic structures of (HF)(2) in a free state and inside argon atom shells Ar-n. For the first stage, molecular dynamics calculations for the (HF)(2) . Ar-62 heterocluster are performed with the help of model potentials HF-HF, Ar-Ar, and Ar-HF. Then, ab initio quantum chemistry analysis is carried out for the smaller systems (HF)(2) . Ar-15 and (HF)(2) . Ar-6 when keeping the argon atoms closest to the trapped dimer. We conclude that the hydrogen-bonded complex (HF)(2) gains some extra stability inside the argon shells, originating primarily from a decrease of intermolecular distance R(FF). Electronic structure calculations are in accord with the changes in dynamical properties, namely, a noticeable increase in the vibrational frequency assigned to the F-F stretching mode (+25 cm(-1)) and decrease in rms deviations for the corresponding coordinate delta(FF). In addition to these changes, the argon atoms of the nearest solvent shell donate a small fraction of electron charge which of the free is spent for an increase of population of the antibonding orbital sigma*(Hf-Ff), monomer unit and shift orbital energies primarily of the lone-pair fluorine species. These shifts are greater than the changes due to geometry alterations and the possible inaccuracies of the calculation scheme. (C) 1997 John Wiley & Sons, Inc. [References: 56]