Ab initio studies of the structure and the interaction of cellulose III_I crystal

摘要

Cellulose is one of the most abundant renewable resources and has high potential for the use as a future energy and materials for the chemical industries. We have investigated the crystal structure of cellulose III_I by using first principle density functional theory (DFT) calculation. The geometry optimization was performed with variable-cell relaxation with the Quantum ESPRESSO program package. We used Perdew-Burke-Ernzerhof (PBE) functional and compared the results with long-range van der Waals type correction term approach (PBE-D). The results are in good agreement with the experimentally obtained crystal structure of cellulose III_I when we used the PBE-D. Although the calculated cell parameters were slightly smaller than the experimental one, it can be well explained to include the thermal expansion effect in the experimental condition of ambient temperature. From the optimized crystal structure, the CH/O interactions included in the crystal structure were evaluated using NBO method. In this work, we showed that the density functional calculation is a powerful method to investigate the detail structure and the arrangement in the crystal and the nano-structured materials.