Dear all,I am a beginner using PLUMED and recently I've been trying to realize some codes for running metadynamics using PLUMED. I submitted the job using the command sbatch run_cpu.sh, which has the content as follows:

#!/bin/sh

#SBATCH --job-name NaCl-m

#SBATCH --qos normal

#SBATCH --nodes=8

#SBATCH --tasks-per-node=1

#SBATCH --cpus-per-task 24

#SBATCH --time 24:00:00

#SBATCH --partition shas

module load gromacs/2018.3

export OMP_NUM_THREADS=24

mpirun -np 8 gmx_mpi mdrun -deffnm NaCl -g NaCl_log.log -ntomp 24 -plumed plumed.dat

What I don't quite understand is the reason for using "export OMP_NUM_THREADS=24" instead of using "export PLUMED_NUM_THREADS=24". For the last command-line, I don't know why there was no command for the file input, for example, some .tpr file produced by grompp. Also, I'm not sure about what the command of "-plumed plumed.dat" was doing (for example, what was it used for, what were the input files and output files). (Did it input the file "plumed.dat"? After some examination, I found it seemed that it not only input this file.) And my last question is, as I enter "plumed --help", it turned out that the command "plumed" was not found. However, I have actually run one metadynamics simulation successfully using PLUMED. Is this error normal? I'm sorry that these questions seem quite dumb. I've tried to find answers, but it was in vain. Thank you all in advance! Wei-Tse