[gmx-users] How to calculate virial in gromacs-4.0?

[xuji]

Hi all

I want to do pressure coupling in my own program.
So These days I read associated codes in Gromacs_4.0 and I find that it
must sum the virial first. In Gromacs-3.3.3 you use the intramolecular shift(graph)
to sum the virial of the covalent bonds, but in Gromacs-4.0 the graph variable seems to be NULL
when run the mdrun with domain decomposition. Is it the true? 
And if it's true how do you sum the virial with the periodic boundary condition 
in Gromacs_4.0 with domain decomposition? Can someone explain the way of summing 
virial in Gromacs_4.0 in detail? Or can you recommend some resoures about summing the virial with 
the periodic boundary condition? 
	
Appreciate any help in advance!

Best
	wishes!
 				

　　　　　　　　xuji
　　　　　　　　xuji at home.ipe.ac.cn
　　　　　　　　　　2008-11-28