hi today i have tried to run the position restrained dynamics using my tpr file grompp -f pr.mdp -c 7/trp_b4pr.gro -p 1/trp.top -o 8/trp_pr.tpr But its showing the error Fatal error: number of coordinates in coordinate file (7/trp_b4pr.gro, 14580) does not match topology (1/trp.top, 0) can anyone help me thanking you santosh