The molecules's behavior in edge plasma is very important in understanding the phenomena near plasma-facing materials. In this paper, various processes of deuterium molecules are discussed and most recent data are applied in the evaluation of molecules' vibrational excitation. For the excitation of the molecules to triplet states, complete sets of vibrationally-resolved cross sections are not available from the literatures. Semi-classical Gryzinski method is used to calculate these cross sections and rate coefficients. Finally, The vibrational distribution of deuterium molecules is calculated by applying a quasi-steady state model for the balance of the vibrational populations. The dependence on the plasma parameters is discussed.
