I have a chain of atoms that I want to constain to move along a line. Obviously, using something to the effect of:
velocity atoms set 0 0 0 units box sum no
set constrain atoms force NULL 0 0
would usually work, however in this case, I am also using a langevin thermostat
compute temp_x chain temp/partial 1 0 0
fix tstat_relax chain langevin 0 300 10 634115
fix_modify tstat_relax temp temp_x
With this fix_modify, I’ve greatly reduced the motion in the perpendicular directions, but there is still motion nonetheless.