[gmx-users] how choose k value in .ppa file

[Marco Deriu]

Hi, gromacs users 

I've a little question about the pulling procedure at constant rate.
I defined pull and reference group both constituted by 18 atoms.
My problem is to define the spring value in .ppa file.
Given that my groups have N atoms, how do I choose a suitable spring value 
quantitative relation (e.g K= kb*T/dx^2...suitable if pull group is 
constituted by 1 atom)  in order to limit the thermal motion of the pull 
group COM to, say, 0.1 nm? 

Marco