Lorentz forces induced by a static magnetic field have negligible effects on results from classical molecular dynamics simulations of aqueous solutions

T Panczyk and PJ Camp, JOURNAL OF MOLECULAR LIQUIDS, 330, 115701 (2021).

DOI: 10.1016/j.molliq.2021.115701

A static external magnetic field is included in molecular dynamics simulations of aqueous solutions, and the effects on static and dynamic properties are determined. It is pointed out that diamagnetic properties are generally negligible if small molecules or ions are considered. Therefore, particular attention is paid to the effects arising from the Lorentz force acting on the (partial) charges on water, atomic ions, and larger molecules in solution. Careful analysis of many macroscopic and microscopic properties is performed for systems in magnetic fields of up to 1 T. None of the properties is found to be significantly affected by the Lorentz force. It is shown that any apparent variations with magnetic-field strength are simply statistical fluctuations. It is emphasized that the magnitude of the Lorentz force is up to eight orders of magnitude smaller than the average force coming from nonmagnetic forces and thermal fluctuations in the liquid phase at normal temperatures. The results are complemented by a theoretical argument which precludes Lorentz-force effects. A discussion of earlier reports of significant magnetic-field effects is presented. (C) 2021 Elsevier B.V. All rights reserved.

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