I’m attempting to implement the following pair style by Hsu and Kremer (DOI: 10.1063/1.5089417):
U(r) = 4\varepsilon \Big[(\frac\sigma r)^{12} - (\frac\sigma r)^{6} + \frac 1 4\Big] for r<2^{1/6}\sigma (WCA potential)
U(r) = \alpha \cos\Big[\pi \frac{r^{2}}{2^{1/3}\sigma^2}\Big] for 2^{1/6}\sigma \leq r < 2^{2/3}\sigma
It’s written in such a way that the energy is discontinuous, but the force is exactly zero at the crossover point. I know that the pressure and the Verlet algorithm use the per-atom forces and not the energy, so they shouldn’t be affected by a constant shift in the potential, but the computed potential energy (e.g., for thermodynamic output or tallying) would be. What would other consequences be in using such a discontinuous potential?