Mechanistic model for the dielectric spectrum of a simple dielectric material

Solvej Knudsen, Jeppe Dyre, Jesper Schmidt Hansen*

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review


In this paper, we perform molecular dynamics simulations of a dielectric fluidic material composed of permanent molecular dipoles. The dielectric spectrum features two peaks at lower frequencies than the system phonon frequency. The primary peak is observed at all temperatures studied and shifts toward lower frequencies as the temperature decreases. During this shift, the secondary peak emerges with a higher peak frequency than the primary peak. The secondary peak amplitude increases as the temperature decreases. Both peaks are dependent on the wavevector; in the small wavevector regime, the primary peak is shifted to higher frequencies as the wavevector squared and the secondary peak amplitude increases as the wavevector increases, but shows no shift in frequency. From the polarisation balance equation, we propose a model for the dielectric spectrum. This captures the spectrum features, and we conjecture that the primary peak is due to dipole moment correlations (Debye-type) and the secondary peak is due to the correlation between the dipole moment and a microscopic local field.
Original languageEnglish
JournalPhilosophical Magazine B: Physics of Condensed Matter, Statistical Mechanics, Electronic, Optical, and Magnetic Properties
Issue number20
Pages (from-to)2556-2567
Number of pages11
Publication statusPublished - 2020

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