AMBER is a highly parallized suite of biomolecular simulation programs which use MPI and OpenMP on CPUs or CUDA (in combination with MPI) to run on GPUs.
Amber is distributed in two parts: AmberTools and Amber. Amber is a package of molecular simulation programs, AmberTools contains a collection of useful software to analyze and modify MD data. You can find a comprehensive manual here.
Examples
AmberTools on CPU with MPI: MMPBSA.py.MPI
The following example runs MMPBSA.py.MPI on 20 identical CPUs. Each of the called Sander jobs (used for surface and energy calculation) may take up to 4G of RAM - for bigger systems this has to be adjusted. The code below runs a 'stability calculation' for a single system. For a comprehensive overview the the AMBER18 manual.
Keep in mind, that MMPBSA calculations are more demanding in terms of memory than MMGBSA jobs.