[gmx-users] two reference groups in pull code

[chris.neale at utoronto.ca]

Dear Bin:

What you request is not currently possible with any distribution up to  
gmx-4.0.7 (I don't know if it is in the cvs). I have a modified  
version of gromacs-4.0.5 that will do this, but we are not  
distributing it yet. We may upload it in the future for incorporation  
into the main distribution, but currently I'm not sure how to do that.

The changes to the gmx-3 source code were not very difficult to get  
this feature, but the changes to gmx-4 were substantial. If you are ok  
to use gmx-3 then you should be able to make the mod yourself in a few  
hours.

Chris.

-- original message --

Dear all:

Reading about the gromacs4 manual, I couldn't figure out a way to
apply two sets of pulling simultaneously in gromacs?
I know you can specify a second group using pull_group2, but it has to
use the same reference group in pull_group0, correct? Then I don't
understand how one can achieve to pull a & b apart, and also c & d
apart at the same time.

Any suggestion will be greatly appreciated.
Thanks,
Bin