The treatment of dispersion terms for solution systems

DFT calculations of reaction mechanisms in solution have always been a hot topic, especially for transition-metal-catalyzed reactions, in which the traditional DFT-D3 method has been extensively employed. The overestimation of the dispersion from the traditional DFT-D3 method leads to a quite low activation free-energy barrier, so it is worth finding a proper way to deal with the dispersion for solution systems. The solvent-solute dispersion is also important for solution systems, and thus it should be calculated together with the solute dispersion. The newly generated solute-solute dispersion energy should be shared equally with the newly formed cavity between two interacting species; therefore, only half of the solute-solute and solvent-solute dispersion terms belong to the solute molecule. The detailed treatment of dispersion correction for solution systems has been fully addressed, and this method has been confirmed with the examples of ligand exchange reactions and catalytic reactions.

Automated summary

DFT calculations of reaction mechanisms in solution, especially for transition-metal-catalyzed reactions, have been extensively studied using the traditional DFT-D3 method. However, the traditional method tends to overestimate dispersion, leading to a low activation free-energy barrier. To address this issue, a proper treatment of dispersion correction for solution systems is proposed, which considers both solute-solute and solvent-solute dispersion. The method has been validated through ligand exchange reactions and catalytic reactions.