Vibrational line shifts of hydrogen halides in a rare gas environment: HF/DF and HCl/DCl in Ar matrices and clusters

Vibrational frequency shifts of fundamental and higher excitations of HF/DF and HCl/DCl in a rare gas environment are calculated using vibrationally dependent atom-molecule potentials. For both octahedral and icosahedral geometry corresponding to a substitutional site in fcc matrices and in medium sized clusters the shift is monitored for an increasing number of up to ten solvation shells. Saturation is reached for the fifth octahedral and for the third icosahedral shell. Good agreement with matrix experiments is found for the shift of the fundamental frequency, while the potential used here does not extrapolate well for the higher excitations of HCl.