Ab initio study of the (H2O...HF)n, n=1-5, complexes.

The equilibrium structures and molecular properties of S-0 and S-1 states of (H2O...HF)(n), n = 1 - 5, complexes were calculated at ab initio SCF and ROHF levels with use of the MONSTERGAUSS program(1). Analysis of electron density distribution for S-0 and S-1 states was performed The excitation energies of S-0 --> S-1 transitions for (H2O...HF)(n), n = 1 - 5, complexes were determinated. The influence of hydrogen bond formation on the shift in the maximum of first absorption band of these complexes was examined. The investigations of electronic excited states of molecules allow solving some analytical problems. One of them it is a problem about identification of substances. In virtue of data about electronic excited states it is possible to carry out a study of photophysical and photochemical processes what take place after photon absorption. From an analysis of experimental data follow that formation of intermolecular hydrogen bond results in the shifts of absorption bands, The shift depends from type of electronic transition. The investigation of the nonriged molecular complexes is important for atmospheric spectroscopy purposes.