Quantum mechanics/molecular mechanics (QM/MM) is a standard computational tool for describing chemical reactivity in systems with many degrees of freedom, including polymers, enzymes, and reacting molecules in complex solvents. However, QM/MM is less suitable for systems with complex MM dynamics due to associated long relaxation times, the high computational cost of QM energy evaluations, and expensive long-range electrostatics. Recently, a systematic coarse-graining of the MM part was proposed to overcome these QM/MM limitations in the form of the quantum mechanics/coarse-grained molecular mechanics (QM/CG-MM) approach. Herein, we recast QM/CG-MM in the density functional theory formalism and, by employing the force-matching variational principle, access the method performance for two model systems: QM CCl4 in the MM CCl4 liquid and the reaction of tert-butyl hypochlorite with the benzyl radical in the MM CCl4 solvent. We find that DFT-QM/CG-MM accurately reproduces DFT-QM/MM radial distribution functions and 3-body correlations between QM and CG-MM subsystems. The free energy profile of the reaction is also described well, with an error < 1-2 kcal/mol. DFT-QM/CG-MM is a general, systematic, and computationally efficient approach to include chemical reactivity in coarse-grained molecular models.
Understanding Dynamics in Coarse-Grained Models: IV. Connection of Fine-Grained and Coarse-Grained Dynamics with the Stokes-Einstein and Stokes-Einstein-Debye Relations
Coarse-Grained Counterions in the Strong Coupling Limit
最近的蒙特卡罗模拟（A. G. Moreira和R. R. Netz：Eur. J. E { \bf 8}（2002）33）在强库仑耦合机制中提出了与泊松-玻尔兹曼图像不同的奇怪的反离子静电：当反离子-反离子排斥相互作用远大于反离子-宏观离子吸引时，宏观离子周围的粗粒度反离子分布仅由后者决定，而前者无关紧要。在这里，我们提供了一个解释显然是矛盾的静电数学操纵的强耦合限制。
