We perform molecular dynamics simulations to investigate the structural (α) relaxation of models of 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF6]) room temperature ionic liquids. To determine the relevance of electrostatic interactions for the dynamical properties, we systematically scale the partial charges of the ions. Observing the structural relaxation of these charge-scaled ionic liquids from high temperature far above the melting point to low temperatures in the viscous regime, we find that the α-relaxation times τq strongly depend on the strength of the electrostatic interactions. The glassy slowdown τq(T) of all systems is successfully described by splitting the apparent activation energies E(T) into a temperature-independent contribution E∞, which characterizes the α relaxation of the high-temperature liquid, and a temperature-dependent contribution Ec(T), which describes the growing cooperativity and increases exponentially upon cooling. For all used partial charges, we find a common relation between the activation energy E∞ and the glass transition temperature Tg, indicating a close link between simple-liquid and viscous-liquid dynamics. To ascertain the origin of the increase of the cooperative contribution Ec(T), we characterize the evolution of space-time characteristics of dynamical heterogeneities upon cooling. It turns out that the length and time scales of spatially heterogeneous dynamics are the same for all studied charge-scaled ionic liquids when plotted as function of τq. Moreover, we find a common relation between Ec and the size of transient clusters of highly mobile ions.
On the relevance of electrostatic interactions for the structural relaxation of ionic liquids: A molecular dynamics simulation study.
Published 2019 in Journal of Chemical Physics
ABSTRACT
PUBLICATION RECORD
- Publication year
2019
- Venue
Journal of Chemical Physics
- Publication date
2019-03-22
- Fields of study
Materials Science, Medicine, Physics, Chemistry
- Identifiers
- External record
- Source metadata
Semantic Scholar, PubMed
CITATION MAP
EXTRACTION MAP
CLAIMS
- No claims are published for this paper.
CONCEPTS
- No concepts are published for this paper.
REFERENCES
Showing 1-94 of 94 references · Page 1 of 1
CITED BY
Showing 1-19 of 19 citing papers · Page 1 of 1