Dear Prof.Dubbeldum
I calculated diffusion coefficient for a binary mixture. The slope of MSD is negative and therefore diffusion coefficient is negative ( for example slope= -0.014 for one or both of species ). Could you please explain the physical meaning of that observation?
I will be so grateful if you guide me.
Net charge of non-zero is a warning, because it needs to be small. Say smaller then 1e-4.
Check that your framework is is neutral and that the molecules are neutral.
Dear Prof.Dubbeldum
I calculated diffusion coefficient for a binary mixture. The slope of MSD is negative and therefore diffusion coefficient is negative ( for example slope= -0.014 for one or both of species ). Could you please explain the physical meaning of that observation?
I will be so grateful if you guide me.
See literature on how to compute diffusion coefficients from MSD. The slops of the MSD at long times can not be negative.
You're probably looking at a situation where MD is not capable of computing diffusion because it is too slow.