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Role of Dynamic Heterogeneities in Ionic Liquids: Insights from All‐Atom and Coarse‐Grained Molecular Dynamics Simulation Studies
Author(s) -
Pal Tamisra,
Vogel Michael
Publication year - 2017
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201700504
Subject(s) - molecular dynamics , hexafluorophosphate , ionic liquid , chemical physics , granularity , relaxation (psychology) , speedup , chemistry , atom (system on chip) , dynamical heterogeneity , statistical physics , computational chemistry , physics , computer science , psychology , social psychology , biochemistry , polymer , organic chemistry , embedded system , glass transition , operating system , catalysis
Abstract We performed molecular dynamics simulations for the room‐temperature ionic liquid 1‐butyl‐3‐methylimidazolium hexafluorophosphate ([Bmim][PF 6 ]). By employing all‐atom (AA) and coarse‐grained (CG) models, we compared the characteristic times of various dynamical modes, from vibration to diffusion, and the importance of dynamical heterogeneities at different levels of chemical resolution and over broad temperature ranges. It was shown that coarse graining leads to a substantial speedup in molecular dynamics, whereas it weakly affects the strength of dynamical heterogeneities. Despite the general speedup, several relationships between dynamical modes on different timescales were preserved. In particular, the heterogeneity timescales of the AA and CG models collapse onto the same curve as a function of the structural ( α ) relaxation time τ α . Moreover, vibrational amplitudes and relaxation times τ α are related at both levels of chemical resolution. We argue that the robustness of these relationships assists the development of dynamically consistent coarse‐graining strategies and justifies the use of simplified models for a theoretical understanding of viscous liquids.