Molecular Dynamics Simulation of Octacosane for Phase Diagrams and Properties via United Atom Scheme

Abstract

We used united atom scheme to build three types of crystalline\nstructures for octacosane (C28H58) and carried out molecular dynamic\nsimulations to investigate their properties. By gradual heating the\nthree polymorphs, we successfully reproduced the sequence of\nexperimentally reported crystalline phase, intermediate rotator phase\nand liquid phase. The obtained structural properties of the phases, such\nas molecule chain morphology, density, chain tilt angle, cell\nanisotropy. We revealed three mechanisms which well described the\nkinetic deformation and expansion during the annealing process.\nFurthermore, our model successfully predicted the melting temperature\nand the heat of fusion. We also reproduced characteristics of the\nrotator phases and the liquid phase, indicating the transferability of\nthe united atom scheme among different condensed phases of octacosane.\nOur methodology represents an effective and efficient means of numerical\nstudy for octacosane and may have implication for other members of the\nn-alkane family.