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Updated: Oct 19, 2025

Analyzing Melts and Fluids from Ab Initio Molecular Dynamics Simulations with the UMD Package
Published on: September 17, 2021
Molecular dynamics simulation of octacosane for phase diagrams and properties via the united-atom scheme
L Dai1, P P Rutkevych2, S Chakraborty1
1Institute of High Performance Computing, Agency for Science, Technology and Research (A*STAR), Singapore. davidwu@ihpc.a-star.edu.sg.
Abstract:
We used the united-atom scheme to build three types of crystalline structures for octacosane (C28H58) and carried out molecular dynamics simulations to investigate their phase properties. By gradually heating the three polymorphs, we managed to reproduce the sequence of experimentally reported crystalline phases and rotator phases. By studying the system density, molecule morphology, chain tilt angle and cell anisotropy, we hypothesized three mechanisms behind the observed system deformations and phase transformations during the annealing process. Furthermore, our model successfully predicted the melting temperature and heat of fusion. We also reproduced the characteristics of the rotator phases and the liquid phase, validating the transferability of the united-atom scheme among the different condensed phases of octacosane. Our methodology represents an effective and efficient means of numerical study for octacosane and may be used for other members of the n-alkane family.
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