title: Composition-dependent dielectric properties of DMF-water mixtures by molecular dynamics simulations.
abstract: In this paper, we study the dielectric properties of water-N,N dimethylformamide (DMF) mixtures over the whole composition range using a molecular dynamics (MD) simulation. The static and microwave frequency-dependent dielectric properties of the mixtures are calculated from MD trajectories of at least 2 ns length and compared to those of available measurements. We find that the short-ranged structural correlation between neighboring water and DMF molecules strongly influences the static dielectric properties of mixtures. In terms of the dynamics, we report time correlation functions for the dipole densities of mixtures and find that their long-time behavior can be reasonably described by biexponential decays, which means the dielectric relaxations of these mixtures are governed by complex multitimescale mechanisms of rotational diffusion. The dipole density relaxation time is a non-monotonic function of composition passing through a maximum around 0.5 mole fraction DMF, in agreement with the measured main dielectric relaxation time of mixtures.
authors.affiliation: College of Electronics and Information Engineering, Sichuan University, Chengdu, 610064, P.R. China.
authors.forename: Guo-Zhu
authors.initials: GZ
authors.lastname: Jia
authors.affiliation: College of Electronics and Information Engineering, Sichuan University, Chengdu, 610064, P.R. China.
authors.forename: Ka-Ma
authors.initials: KM
authors.lastname: Huang
authors.affiliation: College of Electronics and Information Engineering, Sichuan University, Chengdu, 610064, P.R. China.
authors.forename: Li-Jun
authors.initials: LJ
authors.lastname: Yang
authors.affiliation: College of Electronics and Information Engineering, Sichuan University, Chengdu, 610064, P.R. China.
authors.forename: Xiao-Qing
authors.initials: XQ
authors.lastname: Yang
mesh_terms: D000465:Algorithms; D004126:Dimethylformamide / Q000737:chemistry*; D006860:Hydrogen Bonding; D056004:Molecular Dynamics Simulation; D055672:Static Electricity; D013696:Temperature; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water; D004126:Dimethylformamide