Hi Sara, 1 M = 1 mole / dm^3 = 6.022e23 molecules / dm^3 (6.53 nm)^3 = 6.53e-8^3 nm^3 Concentration: 60 / 6.022e23 / 6.53e-8^3 = 0.3578
Alternatively, you can work with the number of solvent molecules 1L H2O = ~55.4 mole 1M = 1 molecule / 55.4 molecules H2O Concentration = 60/(7579./55.4) = 0.4386 The discrepancy between the methods is due to the small volume/amount. Hope it helps, Tsjerk On Thu, Dec 22, 2011 at 6:44 PM, mohammad agha <[email protected]> wrote: > Dear GROMACS users > > I doubt about calculate the concentration of my system. I know that > concentration is calculated from the number of molecules / Avogadro’s number > and divided by volume of box, but I think I calculate wrong, for example in > one of articles had been written: > 7579 water molecules + 60 SDS molecules (surfactant with anionic headgroup) > + 60 Na ion (with a positive charge) in the cubic box with box size = 6.53 > nm , has concentration = 0.4 M. > > May I know how do you calculate this, please? > > Best Regards > Sara > > -- > gmx-users mailing list [email protected] > http://lists.gromacs.org/mailman/listinfo/gmx-users > Please search the archive at > http://www.gromacs.org/Support/Mailing_Lists/Search before posting! > Please don't post (un)subscribe requests to the list. Use the > www interface or send it to [email protected]. > Can't post? Read http://www.gromacs.org/Support/Mailing_Lists -- Tsjerk A. Wassenaar, Ph.D. post-doctoral researcher Molecular Dynamics Group * Groningen Institute for Biomolecular Research and Biotechnology * Zernike Institute for Advanced Materials University of Groningen The Netherlands -- gmx-users mailing list [email protected] http://lists.gromacs.org/mailman/listinfo/gmx-users Please search the archive at http://www.gromacs.org/Support/Mailing_Lists/Search before posting! Please don't post (un)subscribe requests to the list. Use the www interface or send it to [email protected]. Can't post? Read http://www.gromacs.org/Support/Mailing_Lists
