Exciton vs Self-Trapped Exciton

[Gonzolo]

Why would anyone bother with the adjective "Self-Trapped" for an exciton and quote the abbreviation "STE"? Are they identically the same thing or not?

[humanino]

They are different. They can propagate or not. I could not tell much. See for instance :
"Free, quasifree, momentarily trapped, and self-trapped exciton states in molecular crystals", Singh, Jai; Matsui, A., Physical Review B (Condensed Matter), Volume 36, Issue 11, October 15, 1987, pp.6094-6098.