A hybrid Car-Parrinello QM/MM molecular dynamics simulation has been carried out for theWatson-Crick base pair of 9-ethyl-8-phenyladenine and 1-cyclohexyluracil in deuterochloroform solution at room temperature. The resulting trajectory is analyzed putting emphasis on the N-H· · ·N Hydrogen bond geometry. Using an empirical correlation between the N · · ·N-distance and the fundamental NH-stretc...