title: Ab initio studies on the structure of and atomic interactions in cellulose III(I) crystals.
abstract: The crystal structure of cellulose III(I)was analyzed using first-principles density functional theory (DFT). The geometry was optimized using variable-cell relaxation, as implemented in Quantum ESPRESSO. The Perdew-Burke-Ernzerhof (PBE) functional with a correction term for long-range van der Waals interactions (PBE-D) reproduced the experimental structure well. By using the optimized crystal structure, the interactions existed among the cellulose chains in the crystal were precisely investigated using the NBO analysis. The results showed that the weak bonding nature of CH/O and the hydrogen bonding occur among glucose molecules in the optimized crystal structure. To investigate the strength of interaction, dimeric and trimeric glucose units were extracted from the crystal, and analyzed using MP2 ab initio counterpoise methods with BSSE correction. The results estimated the strength of the interactions. That is, the packed chains along with a-axis interacts with weak bonding nature of CH/O and dispersion interactions by -7.50 kcal/mol, and two hydrogen bonds of O2HO2…O6 and O6HO6…O2 connect the neighboring packed chains with -11.9 kcal/mol. Moreover, FMO4 calculation was also applied to the optimized crystal structure to estimate the strength of the interactions. These methods can well estimate the interactions existed in the crystal structure of cellulose III(I).
authors.affiliation: Graduate School of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya-Ku, Yokohama 240-8501, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Ishikawa
authors.affiliation: Graduate School of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya-Ku, Yokohama 240-8501, Japan.
authors.forename: Daichi
authors.initials: D
authors.lastname: Hayakawa
authors.affiliation: Graduate School of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya-Ku, Yokohama 240-8501, Japan.
authors.forename: Hitomi
authors.initials: H
authors.lastname: Miyamoto
authors.affiliation: Central Research Laboratory, Kissei Pharmaceutical Company Ltd, 4365-1 Kashiwabara, Hotaka, Azumino, Nagano 399-8304, Japan.
authors.forename: Motoyasu
authors.initials: M
authors.lastname: Ozawa
authors.affiliation: Central Research Laboratory, Kissei Pharmaceutical Company Ltd, 4365-1 Kashiwabara, Hotaka, Azumino, Nagano 399-8304, Japan.
authors.forename: Tomonaga
authors.initials: T
authors.lastname: Ozawa
authors.affiliation: Graduate School of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya-Ku, Yokohama 240-8501, Japan. Electronic address: k-ueda@ynu.ac.jp.
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Ueda
mesh_terms: D002482:Cellulose / Q000737:chemistry*; D018360:Crystallography, X-Ray; D005947:Glucose / Q000737:chemistry*; D006860:Hydrogen Bonding; D008958:Models, Molecular; D011789:Quantum Theory; D013816:Thermodynamics
chemical_list: D002482:Cellulose; D005947:Glucose
keywords: CH/O interaction; Crystal structure of cellulose III(I); Density functional theory; FMO4; NBO