[gmx-users] two reference groups in pull code

[BIN ZHANG]

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