Assessing the correctness of pressure correction to solvation theories in the study of electron transfer reactions

Abstract

Liquid state theories have emerged as a numerically efficient alternative to costly molecular dynamics simulations of electron transfer reactions in solution. In a recent paper [Jeanmairet et al., Chem. Sci. 10, 2130–2143 (2019)], we introduced the framework to compute the energy gap, free energy profile, and reorganization free energy using molecular density functional theory. However, this technique, as other molecular liquid state theories, overestimates the bulk pressure of the fluid. Because of the very high pressure, the predicted free energy is dramatically exaggerated. Several attempts were made to fix this issue, either based on simple a posteriori correction or by introducing bridge terms. By studying two model half reactions in water, Cl → Cl+ and Cl → Cl−, we assess the correctness of these two types of corrections to study electron transfer reactions. We found that a posteriori correction, because it violates the Variational principle, leads to an inconsistency in the definition of the reorganization free energy and should not be used to study electron transfer reactions. The bridge approach, because it is theoretically well grounded, is perfectly suitable for this type of systems.

Redfield Propagation of Photoinduced Electron Transfer Reactions in Vacuum and Solution

“…Despite that, electron transfer reactions are ubiquitous in all physical systems and play an extremely crucial role in, e.g., the design of molecular electronics and artificial photosynthesis research. − Insight into the dynamics of such reactions is therefore of fundamental interest. Even though numerous experimental and theoretical investigations have been conducted over the past decades, electron transfer reactions are still an extremely active area of research today. − …”

Accurate prediction of hydration free energies and solvation structures using molecular density functional theory with a simple bridge functional

“…As pointed out in Ref. 82 , the PC+ correction modify the SFE without changing the minimization process and it violates the DFT ansatz in the sense that the density minimizing eq. 11 is no longer the one obtained by minimizing eq.…”

Electron transfer of functionalized quinones in acetonitrile

“…However, because the associated solvent configurations have a low probability, it is a tedious task to properly sample the region close to the transition state which makes the construction of free energy profiles computationally demanding. We recently proposed an alternative approach based on molecular density functional theory (MDFT) which is based on functional minimisation rather than on statistical sampling, and thus considerably reduces the computational cost as compared to MD 41,42 .…”