The validity of the linear response theory in solvation dynamics has been investigated by molecular dynamics simulations for a monoatomic solute dissolved in liquid argon. The solvation dynamics for various modifications in the well-depth and size parameters of the solute-solvent interaction potential were described by the response function and the time correlation functions for the mechanical solvation energy in a high density liquid system. The comparison between the two methodologies clearly indicates differences for solvation models involving changes in the solute's size parameter. © 2005 Elsevier B.V. All rights reserved.