Modeling properties of the HF dimer in argon clusters

Abstract

We compare geometry configurations, vibrational properties, and electronic structures of Ž . HF in a free state and inside argon atom shells Ar . the argon atoms closest to the trapped dimer. We conclude that the hydrogen-bonded Ž . complex HF gains some extra stability inside the argon shells, originating primarily 2 from a decrease of intermolecular distance R . Electronic structure calculations are in FF accord with the changes in dynamical properties, namely, a noticeable increase in the Ž y1 . vibrational frequency assigned to the F-F stretching mode q25 cm and decrease in rms deviations for the corresponding coordinate ␦ . In addition to these changes, the FF argon atoms of the nearest solvent shell donate a small fraction of electron charge which is spent for an increase of population of the antibonding orbital U of the free H -F f f 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.

Modeling the Solvation Sites in Rare-Gas Matrices with the Simulated Annealing Monte Carlo Technique

“…It is important to note that one of the structures ( n = 15) with a completely trapped guest system practically coincides with the first solvation shell typical for the bulk (Figure of ref ). On the other hand, no configurations of the type shown in Figure ( n = 17) were distinguished when the matrix was modeled …”

“…An important observation is that practically the same configuration was distinguished as a trapping site for the HF dimer in the argon matrix when the first solvation shell was extracted from the large cluster modeling the bulk (sf. Figure of ref ). A new rearrangement of the solvation site is observed for n = 17 (Figure ).…”

“…This system is an important example of the solvent (Ar) weakly interacting with the solute (HF) 2 which in turn presents the intermolecular hydrogen-bonded complex. Formation of the solvation shells of argon atoms around the hydrogen fluoride monomer HF by a stepwise addition of argon atoms was documented, − however, for the dimer only the first steps in modeling various trapping sites inside argon matrices by using the molecular dynamics simulations were considered. − The second system which models the solvation shells of the SH radical in argon and krypton environments is interesting with respect to the related simulations of the fluorescence spectroscopy of SH in the corresponding matrices. , It is important to note that in this case the search through the excited electronic state potential surface SH(A 2 Σ + )@Rg n is performed. In both examples, the reliable PESs are used consistent with the data of high-resolution molecular spectroscopy for the small (three−four atomic) complexes constituting the fragments of large heteroclusters.…”

“…Formation of the solvation shells of argon atoms around the hydrogen fluoride monomer HF by a stepwise addition of argon atoms was documented, [10][11][12] however, for the dimer only the first steps in modeling various trapping sites inside argon matrices by using the molecular dynamics simulations were considered. [13][14][15] The second system which models the solvation shells of the SH radical in argon and krypton environments is interesting with respect to the related simulations of the fluorescence spectroscopy of SH in the corresponding matrices. 16,17 It is important to note that in this case the search through the excited electronic state potential surface SH(A 2 Σ + )@Rg n is performed.…”

Hybrid diatomics-in-molecules-based quantum mechanical/molecular mechanical approach applied to the modeling of structures and spectra of mixed molecular clusters Arn(HCl)m and Arn(HF)m

“…29 The Ar-HF DIM potential was successfully used for predicting solvent-induced vibrational redshifts of the HF moiety in the Ar n HF clusters 52 as well as for studies of Ar n (HF) 2 . 56,57 The focus of theoretical investigation is now shifting toward larger molecular clusters of the type Rg n (HX) m (m Ͼ2,nϾ12). A straightforward use of ab initio calculations at the proper level, which likely requires approaches higher than the second-order Møller-Plesset ͑MP2͒ and sophisticated basis sets, is prohibitively expensive for such systems.…”