Revised charge equilibration potential for liquid alkanes
Revised charge equilibration potential for liquid alkanes
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DOI：
10.1021/jp8003129
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发表时间：
2008-07-17
影响因子：
3.3
通讯作者：
Patel, Sandeep
中科院分区：
文献类型：
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作者：
Davis, Joseph E.;Warren, G. Lee;Patel, Sandeep
我们提出了一个修正的液体烷烃力场的基础上的电荷平衡形式主义，将局部极化所产生的静电非加性效应。该模型是帕特尔和布鲁克斯早期工作的修订版，专门解决二面角势，静电和伦纳-琼斯（货车德瓦尔斯）力场参数的不足。我们讨论了改进的烷烃骨架扭转势，以匹配高层次的从头算相对构象能量戊烷，己烷和庚烷。我们进一步讨论了静电和Lennard-Jones（货车der Waals）参数的改进，以重现实验极化率，液体密度和己烷的蒸发焓。最后，我们计算了体相液体性质，包括密度，汽化焓，自扩散常数，等温压缩，恒压热容，和NMR T-1弛豫时间，为一系列的直链烷烃，从己烷到十五烷的基础上目前的修订模型。我们还计算了戊烷，己烷和庚烷的水合自由能。修订后的力场提供了一个显着改进的整体描述这些属性相对于原来的参数化。目前的烷烃力场代表了正在进行的CHARMM（哈佛分子力学化学）可极化力场的脂质和完整的膜蛋白的发展平台。
We present a revised liquid alkane force field based on the charge equilibration formalism for incorporating electrostatic nonadditive effects arising from local polarization. The model is a revision of earlier work by Patel and Brooks, specifically addressing deficiencies in the dihedral potential, electrostatic, and Lennard-Jones (van der Waals) parameters of the force field. We discuss refinement of the alkane backbone torsion potential to match high-level ab initio relative conformational energetics for pentane, hexane, and heptane. We further discuss refinement of the electrostatic and Lennard-Jones (van der Waals) parameters to reproduce the experimental polarizability, liquid density, and vaporization enthalpy of hexane. Finally, we calculate bulk liquid properties including densities, vaporization enthalpies, self-diffusion constants, isothermal compressibilities, constant pressure heat capacities, and NMR T-1 relaxation times, for a series of linear alkanes ranging from hexane to pentadecane based on the current revised model. We also compute free energies of hydration for pentane, hexane, and heptane. The revised force field offers a significantly improved overall description of these properties relative to the original parametrization. The current alkane force field represents a platform for ongoing development of a CHARMM (Chemistry at Harvard Molecular Mechanics) polarizable force field for lipids and integral membrane proteins.