Daisuke Matsumoto

Quantum Molecular Dynamics Simulation of Guest Molecules in Gas Hydrate

We performed molecular dynamics simulation on methane, ethane and carbon dioxide hydrate. It was found that in the small cage the methane and ethane are moving near the center of the cavity, while carbon dioxide exists apart from the center of the cavity. We also evaluated the stretching vibrational spectra of the methane in both cages. The calculated spectra are in considerably good agreement with experimental results.

Proton Dynamics Simulation of p‐Chloro and p‐Bromobenzyl Alcohol Crystals

The structure of para‐chlorobenzyl alcohol (pCBA) and para‐bromobenzyl alcohol (pBBA) crystals are characterized by the O–H⋯O hydrogen bonded chains along c axis. The direction of the hydrogen bond in the low temperature phase (LTP) is opposite to that in the room temperature phase (RTP). These transitions are related to the hydrogen bonds. We performed the molecular dynamics simulation of pCBA and pBBA crystals in the LTP and RTP using forces determined by gradient of the energy within semiempirical molecular orbital calculation (PM3). From the distribution of the hydrogen atom of −OH group, we found that the hydrogen atoms in the LTP vibrate at the equilibrium position within one site or asymmetric potential. In the RTP, the hydrogen atoms of pBBA are jumping between the two sites in the symmetric double minimum potential.