Fragility, Stokes-Einstein violation, and correlated local excitations in a coarse-grained model of an ionic liquid - Condensed Matter > Soft Condensed MatterReportar como inadecuado




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Abstract: Dynamics of a coarse-grained model for the room-temperature ionic liquid,1-ethyl-3-methylimidazolium hexafluorophosphate, couched in the united-atomsite representation are studied via molecular dynamics simulations. Thedynamically heterogeneous behavior of the model resembles that of fragilesupercooled liquids. At or close to room temperature, the model ionic liquidexhibits slow dynamics, characterized by nonexponential structural relaxationand subdiffusive behavior. The structural relaxation time, closely related tothe viscosity, shows a super-Arrhenius behavior. Local excitations, defined asdisplacement of an ion exceeding a threshold distance, are found to be mainlyresponsible for structural relaxation in the alternating structure of cationsand anions. As the temperature is lowered, excitations become progressivelymore correlated. This results in the decoupling of exchange and persistencetimes, reflecting a violation of the Stokes-Einstein relation.



Autor: Daun Jeong, M. Y. Choi, Hyung. J. Kim, YounJoon Jung

Fuente: https://arxiv.org/



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