s together, other is independent 
    <LI>
    aniso = all 3 dimensions are independent (anisotropic) 
</UL>
<PRE>
coeffs:   none
               no other parameters required
          nose/hoover xyz
               (1) desired P at beginning of run
               (2) desired P at end of run
          nose/hoover xy or yz or xz or aniso
               (1) desired Px at beginning of run (or NULL, see below)
               (2) desired Px at end of run
               (3) desired Py at beginning of run
         