Evaluation of Heat Storage Materials with J-OCTA

In order to evaluate the performance of sugar alcohols as heat storage materials, latent heat evaluation by molecular simulation was performed using J-OCTA. The target molecule was mannitol. The crystal structure of mannitol (C₆H₁₄O₆) was obtained from the Crystallography Open Database (COD) (http://www.crystallography.net/) as a CIF file. The force field and atomic charges were parameters from a previous study^[1].

Molecular dynamics was used to determine the latent heat at the melting point. First, we perform temperature jumps from the crystalline state to each temperature, and then check whether the material melts at a constant temperature or not. The latent heat of fusion is defined as the difference between the enthalpy in the crystalline state and the enthalpy in the molten state at the minimum temperature at which it melts. The ensemble is NPT_Parrinello_Rahman_Nose_Hoover, so the cell sizes in the X-, Y-, and Z-axes were controlled by pressure independently. The temperature was set from 300 K to 500 K. Calculations were performed for 1 ns at each temperature to see if the melting occurred within 1 ns.