def __init__(self, system, capForce, particleGroup = None):
        if not (pmi._PMIComm and pmi._PMIComm.isActive()) or pmi._MPIcomm.rank in pmi._PMIComm.getMPIcpugroup():
            if (particleGroup == None) or (particleGroup.size() == 0):
                cxxinit(self, integrator_CapForce, system, capForce)
            else:
                cxxinit(self, integrator_CapForce, system, capForce, particleGroup)