Run instructions for NAMD. ntell@grnet.gr After build of NAMD you have an executable called namd2. The best performance and scaling of namd is achieved using hybrid MPI/MT version. On a system with nodes of NC cores per node use 1 MPI task per node and NC threads per task, for example on a 20 cores/node system use 1 MPI process, set OMP_NUM_THREADS or any batch system related variable to 20. Set a variable, for example MYPPN to NC-1, for example to 19 for a 20 cores/node system. You can also try other combinations of TASKSPERNODE/THREADSPERTASK to check. The control file is stmv.8M.memopt.namd for tier-1 and stmv.28M.memopt.namd for tier-0 systems. The general way to run is : WRAPPER WRAPPER_OPTIONS PATH_TO_namd2 +ppn $MYPPN stmv.8M.memopt.namd > logfile WRAPPER and WRAPPER_OPTIONS depend on system, batch system etc. Few common pairs are : CRAY : aprun -n TASKS -N NODES -d THREADSPERTASK Curie : ccc_mrun with no options - obtained from batch system Juqueen : runjob --np TASKS --ranks-per-node TASKSPERNOD --exp-env OMP_NUM_THREADS Slurm : srun with no options, obtained from slurm if the variables below are set. #SBATCH --nodes=NODES #SBATCH --ntasks-per-node=TASKSPERNODE #SBATCH --cpus-per-task=THREADSPERTASK The run walltime is reported at the end of logfile : grep WallClock: logfile | awk -F ' ' '{print $2}'