Mean square displacement Velocity auto-correlation function <r(t)-r(O)2 ()(O) v(O)v(O)) Remark The method of mean square displacement provides a better numerical precision in the calculation of DMean square displacement Velocity auto-correlation function 0 t 1 (0) (0) ( ) (0) v v v t v       t <|r(t) - r(0)|2> Remark: The method of mean square displacement provides a better numerical precision in the calculation of D