[gmx-users] constraint pulling

[Ester Chiessi]

Hi.

I'd like to make shorter the distance between two groups in my system.
I used pull code with the following parameters:

verbose = no
runtype = constraint
group_1 = a_1537-1544
reference_group = a_977-984
constraint_direction = 0 0 1
constraint_rate = -1

My question is:
 is it correct to use a constraint_rate <0 to bring nearer groups?

If I use 'constraint_rate = 1' the distance between groups become longer,
but the calculation with 'constraint_rate = -1' give error after about 600
steps.
Perhaps the constraint_rate is too high ?

Thanks for any help

Ester

Ester Chiessi
Dipartimento di Scienze e Tecnologie Chimiche
Università di Roma Tor Vergata
Via della Ricerca Scientifica
00133 Roma
tel. +39 06 72594462
fax  +39 06 72594328
http://www.stc.uniroma2.it/cfmacro/cfmacroindex.htm