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The influence of cryogenic argon environment on small water clusters was investigated by quantum-chemical simulation of structure and vibrational spectra of water clusters consisting of different numbers of molecules. Comparison of calculation results for vacuum and argon environment shows a red shift of spectral bands in argon. Obtained IR frequencies and intensities for water clusters in argon are compared with experimentally registered FTIR spectra of water trapped in a low-temperature argon matrix.

Alcohol molecules can form hydrogen bonds and arrange in different structures named clusters. The aim of this work is to study the behavior of a cluster structure of alcohols at phase transitions and to elucidate the structure of clusters in the solid and liquid states. The objects of investigation are monohydric alcohols n-pentanol (CH2)4CH3-OH and n-octanol (CH2)7CH3-OH. For the structural analysis of the clusters, the matrix isolation FTIR spectroscopy is used, while the spectroscopic studies of the behavior of different clusters at the solid-liquid phase transition are performed in the liquid and solid states. In order to interpret the experimental spectra, the quantum-chemical calculations with the use of Gaussian03 software (approximation DFT/B3LYP, 6-31G (d, p) are carried out. K e y w o r d s: FTIR Spectra, n-pentanol, n-octanol, cluster structure of alcohols, Gaussian03 software.

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Computer simulations of an argon fcc crystal fragment with embedded water clusters of different sizes are performed using the quantum mechanical DFT/M06-2X method. The effect of the argon matrix on the structural, energy, and spectral parameters of individual water clusters are investigated. The formation energies of (H2O)n@Arm complexes, as well as deformation energies of water clusters and of the argon crystal involved in the embedment, are computed for n = 1–7. Matrix shifts of the IR vibrational frequencies of water clusters isolated in argon matrices are predicted based on the results of the calculations. The predictions indicate a possibility of the formation of small stable water complexes in low-temperature argon matrices.