Department of Biomolecular Engineering, Tokyo Institute of Technology, Yokohama, Kanagawa 226-8501, Japan.
J Chem Phys. 2012 Jul 28;137(4):044110. doi: 10.1063/1.4737860.
A consideration of the surrounding environment is necessary for a meaningful analysis of the reaction activity in large molecular systems. We propose an approach to perform unrestricted Hartree-Fock (UHF) calculations within the framework of the fragment molecular orbital (FMO) method (FMO-UHF) to study large systems with unpaired electrons. Prior to an energy analysis one has to optimize geometry, which requires an accurate analytic energy gradient. We derive the FMO-UHF energy and its analytic gradient and implement them into GAMESS. The performance of FMO-UHF is evaluated for a solvated organic molecule and a solvated metal complex, as well as for the active part of a protein, in terms of energy, gradient, and geometry optimization.
为了对大分子体系中的反应活性进行有意义的分析，必须考虑周围环境。我们提出了一种在碎片分子轨道（FMO）方法（FMO-UHF）框架内进行无限制哈特里-福克（UHF）计算的方法，以研究具有不成对电子的大体系。在进行能量分析之前，必须优化几何形状，这需要准确的解析能量梯度。我们推导出 FMO-UHF 的能量及其解析梯度，并将其实现到 GAMESS 中。根据能量、梯度和几何优化，我们评估了 FMO-UHF 在溶解有机分子、溶解金属配合物以及蛋白质活性部分中的性能。
