2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/147529Basing on the picture of Frenkel excitons in molecular crystals described by the XY-model we consider the linear response of linear cyclic aggregates at finite temperature. The exact results for characteristics of the response are obtained. In particular, we calculate time-dependent two-point correlation functions at finite temperature for the cyclic 1-D XY-model.LaTeX, 23 pages. few misprints were correctedCondensed Mattertext