Error found during the production run

After equilibration, I increased the box length for the air-water interface simulation but I got error as below
“There is no domain decomposition for 48 ranks that is compatible with the given box and a minimum cell size of 6.24938 nm
Change the number of ranks or mdrun option -rdd or -dds
Look in the log file for details on the domain decomposition”

Given command was “gmx_mpi grompp -f md.mdp -c npt1.gro -p -o md_0_1.tpr”

how can I resolve this problem ? please suggest me.

This error is related to how the system is divided among different computing units (MPI ranks). This happens if you try to split the system into too many small parts. The simplest possible solution would be using fewer ranks, often improve efficiency, especially when you hit the limit of domain decomposition. try with 1-2 CPUs.

GROMACS divides the simulation box into smaller cells for parallel processing. Each cell needs to be a certain size based on cutoff radii and other atomic constraints. If you have too many MPI ranks, these cells might become too small, causing issues. Read more here.

Good luck