A coarse-grained model for polyethylene glycol polymer.
A coarse-grained model for polyethylene glycol polymer.
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DOI：
10.1063/1.3664623
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发表时间：
2011-12
期刊：
影响因子：
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通讯作者：
Qifei Wang;D. Keffer;D. Nicholson
中科院分区：
文献类型：
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作者：
Qifei Wang;D. Keffer;D. Nicholson
建立了聚乙二醇链的粗粒模型，并对聚合度为20和40的聚乙二醇链进行了粗粒模型的分子动力学模拟。在该模型中，两个重复单元的聚乙二醇组成为一个CG珠子。首先对聚乙二醇链进行原子分子动力学模拟，得到聚乙二醇链的键合结构概率分布函数(PDF)和非键对关联函数(PCF)。通过对相应的PDF进行简单的反转，得到了键合的CG势。利用基于Ornstein-Zernike方程的Percus-Yevick近似(OZPY(-1))和OZPY(-1)与迭代Boltzmann逆(IBI)方法的组合(OZPY(-1)+IBI)，将CG非键势参数化为PCF。作为一种简单的一步法，OZPY(-1)方法在计算效率上具有优势。使用OZPY(-1)中的势作为初始猜想，IBI方法具有较快的收敛速度。用这两种方法的势对DP=20的聚乙二醇链进行了粗粒分子动力学(CGMD)模拟，满意地再现了相同体系的原子分子动力学模拟的结构性质。与单独使用OZPY(-1)方法相比，OZPY(-1)+IBI方法具有更好的一致性。通过对聚乙二醇DP=40体系的CGMD模拟，进一步验证了新的CG模型和OZPY(-1)+IBI方法的CG势。从聚乙二醇CGMD模拟的聚乙二醇20和40体系的PCF的比较中没有观察到显著的变化，表明电势与链长无关。
A coarse-grained (CG) model of polyethylene glycol (PEG) was developed and implemented in CG molecular dynamics (MD) simulations of PEG chains with degree of polymerization (DP) 20 and 40. In the model, two repeat units of PEG are grouped as one CG bead. Atomistic MD simulation of PEG chains with DP = 20 was first conducted to obtain the bonded structural probability distribution functions (PDFs) and nonbonded pair correlation function (PCF) of the CG beads. The bonded CG potentials are obtained by simple inversion of the corresponding PDFs. The CG nonbonded potential is parameterized to the PCF using both an inversion procedure based on the Ornstein-Zernike equation with the Percus-Yevick approximation (OZPY(-1)) and a combination of OZPY(-1) with the iterative Boltzmann inversion (IBI) method (OZPY(-1)+IBI). As a simple one step method, the OZPY(-1) method possesses an advantage in computational efficiency. Using the potential from OZPY(-1) as an initial guess, the IBI method shows fast convergence. The coarse-grained molecular dynamics (CGMD) simulations of PEG chains with DP = 20 using potentials from both methods satisfactorily reproduce the structural properties from atomistic MD simulation of the same systems. The OZPY(-1)+IBI method yields better agreement than the OZPY(-1) method alone. The new CG model and CG potentials from OZPY(-1)+IBI method was further tested through CGMD simulation of PEG with DP = 40 system. No significant changes are observed in the comparison of PCFs from CGMD simulations of PEG with DP = 20 and 40 systems indicating that the potential is independent of chain length.