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DY: Fachverband Dynamik und Statistische Physik

DY 41: Statistical Physics: General

DY 41.7: Talk

Thursday, March 21, 2024, 11:15–11:30, BH-N 128

A grand canonical hybrid approach to sample explicit solvent in small solvation shells — •Mohammad Rahbar and Christopher J. Stein — Technical University of Munich; TUM School of Natural Sciences, Department of Chemistry, Lichtenbergstr. 4, D-85748 Garching, Germany

Solvation effects significantly influence reactions in solution by modifying potential energy surfaces. Treating the solvent with an implicit model often lacks the depth to provide detailed insights into the structure and statistical fluctuations of the solvent. Explicit solvation models are an alternative approach, where both solute and solvent degrees of freedom are explicitly included. However, this method is limited by computational cost already for simulations with a small number of solvent molecules. Therefore, a hybrid approach that combines implicit and explicit methods may offer a more comprehensive understanding. A recurrent challenge in various hybrid methodologies is the lack of inclusion of statistical solvent fluctuation and heavy reliance on chemical intuition for the structure of the solute-solvent microsolvation shell. In our proposed approach, the grand canonical model plays a crucial role in facilitating the transfer of energy and particles between explicit and implicit domains, ensuring agreement with thermodynamic constraints for the simulated system. Free from ad hoc assumptions, our methodology aims to eliminate any nonphysical biases tied to the explicit set of solvent molecules included in the simulation. We construct a framework for accurately sampling solute and solvent configurations at the QM, QM-MM, or purely MM level in a small solvation shell.

Keywords: grand canonical Monte Carlo; solvation model; QM/MM simulations