The Z-scores have to be converted into vectors. We can think about a quadratic
relation or a linear relation between the Z-scores and the magnitude of the
vectors, but that we will do only after the MD seminar. For now we use a linear
relation. So, as both my two distances are too long, we need four vectors
(A->B; B->A; B->C; C->B). And the two A-B vectors should have
magnitude 4 (units?) and the two B-C vectors should have magnitude 1.8 or
there about. Obviously the two vectors (and vectors are forces, of course)
that work on B should be added up.