Hi everybody, I've a problem...My system consists of high number of  CO2 and low number of N2 and polymer So, after NVT simulation of 25 ns I would like to calculate the diffusion coefficient of CO2 and N2. For low number of N2 i can use the self diffusion coefficient with Einstein relation (7) and with materials studio---->forcite---->analysis i can calculate the mean square displacement. and it's OK!. For the high number of CO2, I cannot use Einstein relation, so in this case I can risolve my problem with the Maxwell-Stefan diffusion (8). how can I resolve my problem? How can I use the eq. (8) ? thanks to everybody