THE MOLECULAR-STRUCTURE OF SODIUM OCTANOATE MICELLES STUDIED BY MOLECULAR-DYNAMICS COMPUTER EXPERIMENTS

In this article we discuss the results of molecular dynamics simulatio ns which were performed to get more information on the physical proper ties of sodium octanoate micelles. The calculations were based on the AMBER forcefield and we succeeded in simulating the dynamic features o f the micelle for a period of 300 ps. The aggregate was surrounded by 870 water molecules and the simulation was performed in the isothermic -isobaric constant NPT ensemble at a temperature of 300 K and a pressu re of 10(5) Pa. From the results, thus obtained, it was possible to ob tain some typical properties of the micelle. It turns out that the ave rage radius of the micelle coincides pretty well with experimental res ults of small angle neutron scattering experiments. It was also possib le to determine the actual conformations of monomers outside and insid e the micelle. These data are in general agreement with nuclear magnet ic resonance studies and with raman scattering experiments. On close i nspection it was found that the micelle attains a slightly ellipsoidal shape.