Abstracts Keynote & Plenary

PO-023
Molecular Dynamics Studies of The Solidβ-HMX: Effects of Hydrostatic Pressure and
Temperature
Shuo Liu1,2, Jing
Chang1,3 and Dong-Qing Wei1
1, College of Life Science and Biotechnology, Shanghai
Jiaotong University, 200240,China
2, Physics Department, Liaoning University, Shenyang, China
3. Institute of Atomic and Molecular Physics, Sichuan University,
Chengdu, 610065, China
The structural, electronic, and mechanical properties of the energetic material β-HMX have
been
studied with the isothermal-isobaric molecular dynamics (NPT-MD) simulation,. The variations of cell
volume, lattice constants of solid β-HMX are presented and discussed at different pressure and
temperature.
Isothermal-isobaric
MD simulations are performed in the temperature range of 5~450K and pressure
range of 0~40GPa. It is found that β-HMX undergoes a phase translation at 360K and 27GPa where
discontuities were observed for the volume and internal geometrical parameters. The N-N bond is
significantly lengthened with increasing temperature, which leads us to believe that it is relevant to the
initial decomposition. There is a larger compression along the c-axis than along the a- and b-axes.
Instead of the COMPASS forcefield used in previous studies[1-4], we tested the applicability of other
two forcefields, i.e. CVFF and PCFF.
References
Lu Lai-Yu, Wei
Dong-Qing, Chen Xiang-Rong, Ji Guang-Fu, Zhang Qing-Ming, Gong Zi-Zheng.The
structural properties of solid β-HMX under compression by the first principle study. Mol. Phys. 2008,
106: 2569
Lu Lai-Yu, Wei Dong-Qing, Chen Xiang-Rong, Ji Guang-Fu, Zhang Qing-Ming, Gong Zi-Zheng. The
Pressure Induced Phase Transition of The Solid β-HMX By The Isothermal-Isobaric Molecular
Dynamics Simulations. Mol. Phys. in press.
Lian Dan, Lu Lai-Yu, Wei Dong-Qing, Zhang
Qing-Ming, Gong Zi-Zheng, Guo Yong-Xin. High
pressure behaviour of β-HMX crystal studied by DFT-LDA. Chin. Phys. Lett. 2008, 25: 899
Lu Lai-Yu, Wei Dong-Qing, Chen Xiang-Rong, Ji Guang-Fu. First-principles calculations of structure
and electronic properties of solid pentaerythritol under pressure. Chin. Phys. Lett. 2008, 25: 3368
PO-024
Molecular dynamics simulations of dipolar fluids in orientationally ordered phases
Lin Gao
1
Co hnology, Shanghai Jiaotong University, China 200240
1,2
and Dong-Qing Wei 1
llege of Life Science and Biotec
2
Physics Department, Liaoning University, Shenyang, China
A recent study shows that the charge separation of dipole particle plays a significant role on the
phase transition of ferroelectric liquid crystal phases. In present paper, molecular dynamics (MD)
simulations were performed for the real dipole model with a reduced distance between the two
charges compared to the previous work, so that it is closer to thepoint dipole model. Much longer
simulations were made compared with earlier work in order to obtain decent results. The potential
energy consists of the site-site Lennard-Jones potential and electrostatic contribution of partial charges.
Results show that chain-like structures in low density regime, nematic, columnar and ferroelectric solid
phase are formed. Detailed analyses were made regarding fluctuation of the order parameters 1p and 2p
as functions of density along with other thermodynamic properties.
References