Hello,
I have read a number of posts related to this topic, but I haven’t found anything as specific as what I mention here.
In the documentation for lj/smooth there is a cautionary note indicating that force smoothing results in discontinuities in the energy. This make sense. However, not having a smoothing function (e.g. lj/cut) also results in a discontinuity (in the force) since as the energy goes to zero the derivative of energy with respect to distance goes to infinity. As a result, as two atoms/particles cross the cutoff, they experience an artificially high repulsive force that imparts extra kinetic energy to the system resulting in an increase in temperature as can be confirmed with an NVE simulation.
Is this discontinuity resulting from a hard cutoff less of a concern than the discontinuity that results from using a switching function? If so, why?
Kind regards,
Sean