About MPI in palabos

for (plint iVertex = 0; iVertex < param.NumV; iVertex++) {
Array<T, 3> force = -reduceImmersedForceOnVertex(*container, iSurface, iVertex) * forceConversion;

When I use this statement, because the function to find the force contains the ivertex parameter of the for loop, I cannot use mpi to compute it in parallel. Is there any solution to this problem?