Solvation shell reorganization is a key component of the dynamics after photoexcitation of a solvated molecule, especially for charge-transfer excitation in polar solvents. These structural dynamics can be directly observed with time-resolved X-ray solution scattering (TR-XSS) experiments. However, disentangling the scattering signal of solvation-shell reorganization can be challenging, especially for systems containing only light atoms. Here, nonequilibrium molecular dynamics simulations of a hemithioindigo chromophore in acetonitrile are used to investigate the solvation dynamics upon photoinduced charge transfer as well as vibrational excitation and cooling, and to characterize the corresponding time-resolved X-ray scattering signals. It is found that charge transfer induces rapid reorientation of the first solvation shell (0.15-0.2 ps) followed by slower reorientational and solvent redistribution within and between shells (1-2 ps). An analysis of the volume around the solute excluded to the solvent reveals an initial contraction of the solvation shell, followed by transient rebound within the first 0.4 ps, and then slower contraction. Instantaneous vibrational excitation expands the excluded volume, reaching a maximum near 0.4 ps, followed by contraction during cooling with biexponential relaxation. Low-q features in both the calculated solute-solvent and solvent-solvent scattering signals reflect rearrangements within the first solvation shell and redistribution across shells, while higher-q solute-solvent features more closely follow local first-shell restructuring. These results show that TR-XSS can provide information on both local solvent rearrangements and redistribution across solvation shells and demonstrate that interpreting the scattering signals requires accounting for changes in solvent packing induced by vibrational heating and cooling of the solute.
Computational Study of Li+ Solvation Structures in Fluorinated Ether, Non-Fluorinated Ether, and Organic Carbonate-Based Electrolytes at Low and High Salt Concentrations
Accurate Prediction of Free Solvation Energy of Organic Molecules via Graph Attention Network and Message Passing Neural Network from Pairwise Atomistic Interactions
University of Michigan（密歇根大学）；Stanford University（斯坦福大学）
Calculated state-of-the art results for solvation and ionization energies of thousands of organic molecules relevant to battery design
Ecole Polytechnique Fédérale de Lausanne（洛桑联邦理工学院）；University of Vienna（维也纳大学）；Uppsala University（乌普萨拉大学）；Vector Institute for Artificial Intelligence（人工智能向量研究所）；University of Toronto（多伦多大学）；Technische Universität Berlin（柏林工业大学）
Department of Engineering Physics and Computation, TUM School of Engineering and Design, Technical University of Munich（工程物理与计算系，TUM工程与设计学院，慕尼黑技术大学）；Atomistic Modeling Center (AMC), Munich Data Science Institute (MDSI), Technical University of Munich（原子建模中心（AMC），慕尼黑数据科学研究所（MDSI），慕尼黑技术大学）
Predicting solvation free energies with an implicit solvent machine learning potential
Faculty of Physics and Center for NanoScience, Department of Veterinary Sciences, Ludwig-Maximilians-Universität München（物理系和纳米科学中心、兽医学系，路德维希-马克西米利安大学慕尼黑）；Atomistic Modeling Center, Munich Data Science Institute, Technical University of Munich（原子模型中心、慕尼黑数据科学研究所，慕尼黑技术大学）；Multiscale Modeling of Fluid Materials, Department of Engineering Physics and Computation, TUM School of Engineering and Design, Technical University of Munich（多尺度流体材料建模，工程物理与计算系，TUM工程与设计学院，慕尼黑技术大学）
