This package contains 2 fix commands, "fix qtb" and 
"fix qbmsst" which involve quantum nuclear effects.

What is quantum nuclear effects (in molecular dynamics 
simulation)?
	Quantum treatment of the vibrational modes will 
	introduce zero point energy into the system, alter 
	the energy power spectrum and bias the heat capacity 
	from the classical limit. classical MD leaves out 
	these effects completely and thus need to be corrected.
	
When should I consider quantum nuclear effects in 
my simulation?
	(1) When you want to model systems at temperatures 
	lower than their classical limits. This is especially 
	important for materials with a large population of 
	hydrogen atoms and thus higher classical limits.

	(2) In MD simulations when temperatures ramp up 
	across (or starting from somewhere close to) the 
	classical limits, tiny differences between the 
	classical and quantum heat capacity can accumulate 
	and cause the final state to deviate (could be as 
	large as 30 %).

What command should I use regarding these two cases?
	(1) "fix qtb" provides quantum nulcear correction 
	through a colored thermostat and can be used with 
	other time integration schemes like fix nve or 
	fix nph. In this case, you tell "fix qtb" the temperature 
	and the other time integration scheme either the 
	pressure ("fix nph") or the volume ("fix nve").

	(2) "fix qbmsst" deals with shock MD simulations 
	in which cases the temperature may increase a lot. 
	It enables quantum nuclear correction of a multi-scale 
	shock technique simulation by coupling the quantum 
	thermal bath with the shocked system. It is an independent 
	command from "fix msst" and does not assume that 
	the SHOCK package has been installed.

	See the doc page for the fix qtb and fix qbmsst 
	command for detailed usage instructions.

Where can I find examples of these two commands?
	There are example scripts for using this package in
	examples/USER/qtb, including one "fix qtb" and one 
	"fix qbmsst" example for each of alpha quartz and 
	methane. Running the alpha quartz example requires 
	installation of the kspace package while the methane 
	example requires the REAX package for the force field. 

Authors Information and Contact
	The person who created this package is Yuan Shen 
	(sy0302 at stanford.edu) at Stanford University. 
	Contact him directly if you have questions.
