Merck molecular force field. IV. conformational energies and geometries for MMFF94
Merck molecular force field. IV. conformational energies and geometries for MMFF94
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DOI：
10.1002/(sici)1096-987x(199604)17:5/6
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发表时间：
1996-04
影响因子：
3
通讯作者：
T. Halgren;R. Nachbar
中科院分区：
文献类型：
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作者：
T. Halgren;R. Nachbar
本文介绍了MMFF 94的参数化和性能的构象能，旋转障碍，和平衡扭转角。它描述了从高质量计算数据中推导扭转参数的过程，并描述了MMFF 94再现计算和实验数据的能力，后者特别是与MM 3相关的数据。计算数据包括：（i）MP2/6 - 31 G * 几何构型下基于“MP4 SDQ/TZP”计算（在高度相关的MP4 SDQ水平的定义近似下的三重ζ加极化计算）的构象能的10250次比较;以及（ii）MP2/6 - 31 G * 几何构型衍生的几何构型下“扭转轮廓”结构的101200次MP2/TZP比较。扭转参数是在使用完整可用计算数据集的约束最小二乘拟合中得出的，从而确保获得完全最优的参数集。最终参数再现了“MP4 SDQ/TZP”和MP2/TZP计算数据，均方根（rms）偏差分别为0.31和0.50千卡/摩尔。此外，MMFF 94再现了一组37个实验气相和溶液构象能、构象能和自由能，均方根偏差为0.38 kcal/mol;为了比较，“MP4 SDQ/TZP”计算和MM 3各自给出了0.37 kcal/mol的均方根偏差。此外，MMFF 94再现了28个实验确定的旋转障碍的均方根偏差为0.39千卡/摩尔。考虑到实验构象能和转动势垒的多样性，以及某些情况下实验误差的明显迹象，MMFF 94的结果似乎很好。然而，MMFF 94在处理将高极性官能团紧密靠近的多官能化合物时遇到了更大的困难，可能是因为它像其他常用的力场一样，大大简化了静电相互作用的描述。对MMFF 94函数形式的改进提出了一些建议。John Wiley & Sons，Inc.
This article describes the parameterization and performance of MMFF94 for conformational energies, rotational barriers, and equilibrium torsion angles. It describes the derivation of the torsion parameters from high‐quality computational data and characterizes MMFF94's ability to reproduce both computational and experimental data, the latter particularly in relation to MM3. The computational data included: (i) ∼ 250 comparisons of conformational energy based on “MP4SDQ/TZP” calculations (triple‐zeta plus polarization calculations at a defined approximation to the highly correlated MP4SDQ level) at MP2/6‐31G* geometries; and (ii) ∼ 1200 MP2/TZP comparisons of “torsion profile” structures at geometries derived from MP2/6‐31G* geometries. The torsion parameters were derived in restrained least‐squares fits that used the complete set of available computational data, thereby ensuring that a fully optimal set of parameters would be obtained. The final parameters reproduce the “MP4SDQ/TZP” and MP2/TZP computational data with root mean square (rms) deviations of 0.31 and 0.50 kcal/mol, respectively. In addition, MMFF94 reproduces a set of 37 experimental gas‐phase and solution conformational energies, enthalpies, and free energies with a rms deviation of 0.38 kcal/mol; for comparison, the “MP4SDQ/TZP” calculations and MM3 each gives a rms deviation of 0.37 kcal/mol. Furthermore, MMFF94 reproduces 28 experimentally determined rotational barriers with a rms deviation of 0.39 kcal/mol. Given the diverse nature of the experimental conformational energies and rotational barriers and the clear indications of experimental error in some cases, the MMFF94 results appear excellent. Nevertheless, MMFF94 encounters somewhat greater difficulty in handling multifunctional compounds that place highly polar functional groups in close proximity, probably because it, like other commonly used force fields, too greatly simplifies the description of electrostatic interactions. Some suggestions for enhancements to MMFF94's functional form are discussed. © 1996 John Wiley & Sons, Inc.