Ionic velocities in an ionic liquid under high electric fields using all-atom and coarse-grained force field
John W Daily1, Michael M Micci
1Department of Mechanical Engineering, Center for Combustion and Environmental Research, University of Colorado at Boulder, Colorado 80309-0427, USA. john.daily@colorado.edu
The Journal of Chemical Physics
|September 11, 2009
Summary
Molecular dynamics simulations reveal the Wien effect in the ionic liquid EMIM-BF(4) at high electric fields. A modified theory helps explain this phenomenon in ionic liquids, offering computational savings with coarse-graining methods.
Area of Science:
- Computational chemistry
- Materials science
- Electrochemistry
Background:
- Ionic liquids (ILs) are salts that are liquid at low temperatures, with unique properties.
- Understanding their behavior under high electric fields is crucial for applications.
- The Wien effect, a decrease in electrical resistance at high fields, is known in conventional electrolytes.
Purpose of the Study:
- To estimate ionic velocities and electrical conductivity in 1-ethyl-3-methylimidazolium/tetraflouroborate (EMIM-BF(4)) using molecular dynamics.
- To investigate the presence and behavior of the Wien effect in this ionic liquid.
- To evaluate the applicability of existing theories to describe the Wien effect in ILs.
Main Methods:
- All-atom and coarse-grained molecular dynamics simulations were performed.
- Simulations were conducted under high electric field conditions.
- The Wilson theory was adapted to analyze the observed phenomena.
Main Results:
- The Wien effect was observed in EMIM-BF(4) at high electric fields.
- The original Wilson theory did not accurately describe the data for ionic liquids.
- A modified Wilson theory qualitatively explained the observed Wien effect.
- Coarse-graining methods offered significant computational savings despite increased noise.
Conclusions:
- Molecular dynamics is a viable tool for studying ionic liquid behavior under electric fields.
- The Wien effect occurs in EMIM-BF(4) and can be qualitatively described by a modified theory.
- Coarse-graining presents an efficient approach for simulating ionic liquids, balancing accuracy and computational cost.
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