We examine the performance of recent potential energy surfaces for the C-2 Sigma(+) state of LiAr, obtained through pseudopotential and configuration interaction calculations, to describe the relaxation dynamics of argon matrices doped with lithium after excitation to the first Rydberg state of the diatomic molecule. Our results show that the absorption band and the dynamical behavior of the system are quite sensitive to the intermediate energy barrier while differences due to the second well are very small. It points to the feasibility to employ many-body response to photoexcitation in condensed media to study the topology of alkali-rare gas excited states. (c) 2006 Elsevier B.V. All rights reserved.