has one additional affect, namely
  that no angle forces for any angle of type angletype are computed
  (since it is assumed those angles will be frozen by being SHAKEn), thus
  it will likely cause unintended behavior if the bonds in some atom pairs
  within angles of type angletype do not have the appropriate bondtype,
  since they will not be SHAKEn but neither will the angle force by computed
for style region, a coeff of INF means + or - infinity (all the way 
  to the boundary)
an atom can be assigned 