it is important to recognize how MPICH and OpenMPI are different, i.e. that they are designed to meet different needs. MPICH is supposed to be high-quality reference implementation of the latest MPI standard and the basis for derivative implementations to meet special purpose needs. OpenMPI targets the common case, both in terms of usage and network conduits.
The partial charges of neutral and charged molecules are obtained by fitting their values toreproduce the electrostatic potential of a single molecule (charged or neutral) in a vacuum.