The Molecular Structure of Sodium Octanoate Micelles Studied by Molecular Dynamics Computer Experiments

In this article we discuss the results of molecular dynamics simulations which were performed to get more information on the physical properties of sodium octanoate micelles. The calculations were based on the AMBER forcefield and we succeeded in simulating the dynamic features of 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 pressure of 10⁵ Pa. From the results, thus obtained, it was possible to obtain some typical properties of the micelle. It turns out that the average radius of the micelle coincides pretty well with experimental results of small angle neutron scattering experiments. It was also possible to determine the actual conformations of monomers outside and inside the micelle. These data are in general agreement with nuclear magnetic resonance studies and with raman scattering experiments. On close inspection it was found that the micelle attains a slightly ellipsoidal shape.