摘要
采用基于简立方晶格模型的Wang-Landau算法,研究了均聚物单链体系的相行为.计算了不同链长(N)系统的态密度,并基于此计算了系统的自由能、内能、熵和比热等热力学量以及回旋半径及均方末端距.从比热随温度的变化曲线可知,随着温度的降低,大N系统将经历coil-globule及liquid-solid的转变.分析不同N系统的coil-globule转变温度及liquid-solid转变温度并经外延可知,在热力学极限(N→∞)下,coil-globule及liquid-solid两个转变温度并不重合,这不同于Binder K等人基于多键涨落模型得到的结论,而与Vogel T等人基于简立方晶格模型采用链生长方法得到的结论一致.
The phase behavior of single homopolymer chain systems is studied by WangLandau algorithm, based on a simple cubic lattice model. First of all, the density of states is calculated for systems with different chain length （N）, and then free energy, internal energy, entropy and specific heat are calculated as a function of temperature （T）. Meantime, the micro-canonical average and canonical average of gyration radius and end-end distance are calculated. From the dependence of specific heat on T, as T decreases, the large N system undergoes transitions from a coil to a globule phase and then to a solid phase. By analyzing the coil- globule and liquid-solid transition temperatures for systems with different chain lengths, two transition temperatures do not coincide in the thermodynamic limit （infinite chain length）. This result is not consistent with that of Binder K et al based on bond- fluctuation model, but agrees with the result from sophisticated chain-growth methods by Vogel T et al.
出处
《南开大学学报（自然科学版）》
CAS
CSCD
北大核心
2012年第2期45-50,共6页
Acta Scientiarum Naturalium Universitatis Nankaiensis
基金
国家自然科学基金(20925414
20990234)
