[gmx-users] Themostat problem

[qiao rui]

Dear All:

	I am trying to use Nose-Hoover thermostat for my simulation
system, where I have ~1500 water molecules, ~50 Na+ and ~50~ Cl- ions. I
used the following paramters:
	tau_t = 0.05 ps; t_ref = 300K for each group.

	Using g_energy, I got the following statistics:

Energy             Average       RMSD     Fluct.      Drift  Tot-Drift
-------------------------------------------------------------------------------
T-SOL              300       4.91058    4.90895 -0.000912265   -0.437889
T-Na               300.003   279.733    243.602   0.992376    476.343
T-Cl               299.997    385.632    373.082    0.70422    338.027

	It seems that the fluctuation of the temperature for Na+ and Cl-
is huge. Is there some way to solve the problem?

	Another question I have is: is it possible to just couple the x-
and y- degree of freedom with the themostat instead of coupling all the
three directions to the thermostat?

	sincerely,

	Rui Qiao
------------------------
Rui Qiao
Research Assistant
Beckman Institute, UIUC