Problem about command fix lj/wall93

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1

Hi,
I have a question about the command fix lj/wall93.
The manual said for the fix lj/wall command, the units keyword determines the meaning of the distance units used to define a wall position. However, I wander if it also determines the energy units, as the epsilon is energy or energy/distance^2 units.
Because I’m doing a simulation that the units is real, not lj, so I don’t know whether the command “fix wallhi all wall/lj93 xlo v_x 1.0 1.0 2.5 units box” can be used in my system without conversion. I mean, do I need to calculate the value of epsilon for the units real?
I don’t know if I am making myself clear. Thanks for reading my question!

Yuan

2

The units keyword in the fix wall.lj93 command only
affects the param that it states, i.e. the wall position param.

However the units command itself (e.g. for real for lj) affects
nearly every param you use in your script. It certainly affects
the LJ and sigma params in this command, the same as
it does for the pair coeff comand. Values of 1.0 and 1.0 for
eps and sigma are way off for real units, whether for the
pair coeff command or this command.

Steve

3

Hi,Steve,
I understand. Thank you very much for your help!