 partition work between short-range and long-range routines
accuracy criterion effectively determines how many k-space vectors are used
  to approximate the energy and forces
for PPPM, accuracy criterion determines mesh spacing (see &quot;particle mesh&quot;
  command)
3-d periodic boundary conditions are normally used in conjunction with
  Ewald and PPPM, see &quot;slab volume&quot; command for 2-d Ewald/PPPM
cannot use any Coulomb styles other than none with nonbond style = lj/shift or
  nonbond style = s