Diffusion activation energy versus the favourable energy in two-order-parameter model:A molecular dynamics study of liquid Al  

作　　者：李宜德 郝清海 曹启龙 刘长松 

机构地区：[1]Key Laboratory of Materials Physics,Institute of Solid State Physics,Chinese Academy of Sciences [2]School of Physics and Material Science,Anhui University

出　　处：《Chinese Physics B》2010年第8期483-488,共6页中国物理B（英文版）

基　　金：Project supported by the National Natural Science Foundation of China(Grant Nos.10674135,10874182 and 50803066);the Foundation of the Education Committee of Anhui Province,China(Grant Nos.KJ2010A031 and KJ2010A012);the Funds from the Centre of Computational Science,Hefei Institutes of Physical Sciences

摘　　要：In the present work, we find that both diffusion activation energy Ea（D） and Ea（S^ex） increase linearly with pressure and have the same slope （0.022±0.001 eV/GPa） for liquid Al. The temperature and pressure dependence of excess entropy is well fitted by the expression -S^ex （T, P）/kB = a（P）＋ b（P）T ＋ c（P） exp（Ef/kBT）, which together with the small ratio of Ef/kB T leads to the relationship of excess entropy to temperature and pressure, i.e. Sex ~ -cEf/T, where c is about 12 and Ef （= △E - P△V） is the favourable energy. Therefore, there exists a simple relation between Ea（S^ex） and Ef, i.e. Ea（S^ex） ≈ cEf.In the present work, we find that both diffusion activation energy Ea（D） and Ea（S^ex） increase linearly with pressure and have the same slope （0.022±0.001 eV/GPa） for liquid Al. The temperature and pressure dependence of excess entropy is well fitted by the expression -S^ex （T, P）/kB = a（P）＋ b（P）T ＋ c（P） exp（Ef/kBT）, which together with the small ratio of Ef/kB T leads to the relationship of excess entropy to temperature and pressure, i.e. Sex ~ -cEf/T, where c is about 12 and Ef （= △E - P△V） is the favourable energy. Therefore, there exists a simple relation between Ea（S^ex） and Ef, i.e. Ea（S^ex） ≈ cEf.

关 键 词：activation energy favourable energy molecular dynamics simulation 

分 类 号：O469[理学—凝聚态物理]