The driving force of the oriented growth on aligned poly(tetrafluoroethylene) [PTFE] surfaces has been investigated. Oriented thin films have been obtained by depositing several linear dye molecules on friction-transferred PTFE layers through evaporation. The orientational order has been estimated from the dichroism in their polarized UV-vis absorption spectra, whereas also it has been calculated from a molecular dynamics (MD) simulation. The dynamics simulates, adsorption of each single dye molecule on a surface consisting of eight C32F66 chains uniaxially aligned in a plane. A shallow "atomic groove" is formed between two adjacent chains owing to their weak helix and it often traps some dye molecules, thereby orientating them along the chains. The order values calculated from this simulation correlate well with those estimated from the dichroism, thus revealing that the groove accounts for the orientation of these dyes through the deposition.