A comparison is made between the lattice dynamics of cobalt embedded in silver, studied by Mössbauer spectroscopy and by classical molecular dynamics (MD). The MD is achieved in the NPT ensemble by means of the Rahman Parrinello technique which accounts for the temporal fluctuations of all the components of the stress tensor. Atomic interactions are described within an empirical embedded atom model.The mean square thermal vibration amplitude of substitutional Co is calculated and found to compare well with experimental value extracted from Mössbauer spectroscopy. Mössbauer spectroscopy shows the Debye temperature to be cluster size dependent and a comparison with MD suggests the possibility of quantitative cluster size estimates.