Geometry optimization with QM/MM, ONIOM, and other combined methods.: I.: Microiterations and constraints
Geometry optimization with QM/MM, ONIOM, and other combined methods.: I.: Microiterations and constraints
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DOI：
10.1002/jcc.10156
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发表时间：
2003-04-30
影响因子：
3
通讯作者：
Frisch, MJ
中科院分区：
文献类型：
--
作者：
Vreven, T;Morokuma, K;Frisch, MJ
混合能量法，如QM/MM和ONIOM，将联合收割机不同层次的理论结合到一个计算中，在描述大型系统方面非常成功。几何优化方法可以利用将这些计算划分为在量子力学（QM）理论水平下处理的区域和通过诸如分子力学（MM）的廉价方法处理的较大的剩余区域。对于QM区域中的每个优化步骤，可以采用一系列微迭代来完全优化MM区域。笛卡尔坐标用于MM区域，并被选择为使得QM区域的内部坐标在微迭代期间保持恒定。MM区域的坐标被增强以允许QM区域的刚体平移和旋转。如果MM区域中的任何原子受到约束，这是必不可少的，但它也提高了无约束优化的效率。由于微迭代，需要特别注意QM区域中的优化步骤，使得系统在优化过程中保持在相同的局部谷。与微迭代，约束条件和步长控制的优化方法进行了说明细菌视紫红质和其他系统的计算。(C)2003 Wiley Periodicals，Inc.
Hybrid energy methods such as QM/MM and ONIOM, that combine different levels of theory into one calculation, have been very successful in describing large systems. Geometry optimization methods can take advantage of the partitioning of these calculations into a region treated at a quantum mechanical (QM) level of theory and the larger, remaining region treated by an inexpensive method such as molecular mechanics (MM). A series of microiterations can be employed to fully optimize the MM region for each optimization step in the QM region. Cartesian coordinates are used for the MM region and are chosen so that the internal coordinates of the QM region remain constant during the microiterations. The coordinates of the MM region are augmented to permit rigid body translation and rotation of the QM region. This is essential if any atoms in the MM region are constrained, but it also improves the efficiency of unconstrained optimizations. Because of the microiterations, special care is needed for the optimization step in the QM region so that the system remains in the same local valley during the course of the optimization. The optimization methodology with microiterations, constraints, and step-size control are illustrated by calculations on bacteriorhodopsin and other systems. (C) 2003 Wiley Periodicals, Inc.