Résumé
For chemistry networks describing the reactions for the early universe and especially for accuratemodels of the enrichment of deuterated molecules observed, we need to know in detail manystate-to-state rate coeffcients. Today most of the rate coeffcients of interesting reactions are stillunknown or with a poor accuracy. For example, the uncertainty about the rate coeffcient for thereaction directly affects model predictions for the HD abundance and thereby the cooling rate ofthe primordial gas. It is therefore of astrophysical importance to determine an accurate value ofthese rates, and helping to understand the cooling requires a complete set of the state-to-state ratecoefficients as well as the total rate coefficient.In this talk, I will present the Time Independent Quantum Mechanical (TIQM)and Statistical Quantum Mechanical (SQM) results for the D++H2 reaction at low temperatureusing an accurate ab initio potential. The state to state cross sections at low collisional energiesand rate coefficients at low temperature have been computed and are compared to the availableexperimental data.