Hi,all
I’m not quite understand these interpretation as follows in the manual. Does anybody have more clear explanations about this?
I have a system with water and graphene in it, but the initial positions of some water are too closed, so I first used minimize command to relax
the system. Then I used fix shake command for following simulations. The simulation goes well, but I don’t know what does “an error” mean, does it mean
the results lammps gives are wrong?
thanks,
xiong
"It is an error to use fix shake with minimization because it turns off bonds that should be included in the potential
energy of the system. The effect of a fix shake can be approximated during a minimization by using stiff spring
constants for the bonds and/or angles that would normally be constrained by the SHAKE algorithm."
Hi,all
I'm not quite understand these interpretation as follows in the manual. Does
anybody have more clear explanations about this?
very simple. fix shake does not do anything, if you do a
minimization. that can severely deform your geometries,
unless you use large enough force constants in your
bonds and angles. usually those force constants are
ignored for shake and only the equilibrium distance or
angle used (as input for shake).
I have a system with water and graphene in it, but the initial positions of
some water are too closed, so I first used minimize command to relax
the system. Then I used fix shake command for following simulations. The
simulation goes well, but I don't know what does "an error" mean, does it
mean the results lammps gives are wrong?
the results of the minimization, yes, but for the rest it doesn't
matter so much.
axel.