Titel
Exploring Routes to Enhance the Calculation of Free Energy Differences via Non-Equilibrium Work SQM/MM Switching Simulations Using Hybrid Charge Intermediates between MM and SQM Levels of Theory or Non-Linear Switching Schemes
Autor*in
Abstract
Non-equilibrium work switching simulations and Jarzynski’s equation are a reliable method for computing free energy differences, Δ𝐴low→high, between two levels of theory, such as a pure molecular mechanical (MM) and a quantum mechanical/molecular mechanical (QM/MM) description of a system of interest. Despite the inherent parallelism, the computational cost of this approach can quickly become very high. This is particularly true for systems where the core region, the part of the system to be described at different levels of theory, is embedded in an environment such as explicit solvent water. We find that even for relatively simple solute–water systems, switching lengths of at least 5 ps are necessary to compute Δ𝐴low→high reliably. In this study, we investigate two approaches towards an affordable protocol, with an emphasis on keeping the switching length well below 5 ps. Inserting a hybrid charge intermediate state with modified partial charges, which resembles the charge distribution of the desired high level, makes it possible to obtain reliable calculations with 2 ps switches. Attempts using step-wise linear switching paths, on the other hand, did not lead to improvement, i.e., a faster convergence for all systems. To understand these findings, we analyzed the solutes’ properties as a function of the partial charges used and the number of water molecules in direct contact with the solute, and studied the time needed for water molecules to reorient themselves upon a change in the solute’s charge distribution.
Stichwort
free energyindirect thermodynamic cyclenon-equilibrium simulation
Objekt-Typ
Sprache
Englisch [eng]
Persistent identifier
Erschienen in
Titel
Molecules
Band
28
Ausgabe
10
ISSN
1420-3049
Erscheinungsdatum
2023
Publication
MDPI AG
Erscheinungsdatum
2023
Zugänglichkeit
Rechte
Rechteangabe
© 2023 by the authors
Universität Wien | Universitätsring 1 | 1010 Wien | T
+43-1-4277-0