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Magnetized plasmas are well known to exhibit a rich spectrum of collective modes. Here, we focus on the density modes in dense or cold plasmas, where strong coupling effects alter the mode spectrum known from traditional weakly coupled plasmas. In particular, we study the dynamic structure factor (DSF) of the magnetized one‐component plasma with molecular dynamics simulations. Extending our previous results (H. Kählert and M. Bonitz, Phys. Rev. Research 2022, 4, 013197), it is shown that Bernstein modes can be observed in the weakly magnetized regime, where they are found below the upper hybrid frequency, provided the coupling strength is sufficiently low. We investigate the DSF for a variety of different wave numbers and plasma parameters and show that even small magnetization can give rise to a strong zero‐frequency mode perpendicular to the magnetic field and change the dispersion as well as the damping of the upper hybrid mode. [ABSTRACT FROM AUTHOR]

The study of matter under extreme densities and temperatures as they occur, for example, in astrophysical objects and nuclear fusion applications has emerged as one of the most active frontiers in physics, material science, and related disciplines. In this context, a key quantity is given by the dynamic structure factor S(q, ω), which is probed in scattering experiments—the most widely used method of diagnostics at these extreme conditions. In addition to its importance for the study of warm dense matter, the modelling of such dynamic properties of correlated quantum many-body systems constitutes an important theoretical challenge. Here, we report a roton feature in the dynamic structure factor S(q, ω) of the warm dense electron gas, and introduce a microscopic explanation in terms of an electronic pair alignment model. Our results will have direct impact on the interpretation of scattering experiments and may provide insights into the dynamics of a number of correlated quantum many-body systems such as ultracold helium, dipolar supersolids, and bilayer heterostructures. Accurate understanding of the dynamics of correlated quantum many-body systems is of interest in many fields. Here the authors explain the exchange–correlation induced red-shift and incipient roton feature of the dynamic structure factor of the warm dense electron gas in terms of electronic pair alignment model. [ABSTRACT FROM AUTHOR]

The dynamic structure factor (DSF) of the three-dimensional Yukawa one-component plasma is studied with molecular and Langevin dynamics simulations at moderate and strong coupling. The focus of the investigation is on the dependence of the DSF on the friction coefficient in different frequency and wavenumber regimes. At small to intermediate wavenumbers, frictional damping reduces the strength of the sound peak and leads to a red-shift of its frequency. In an intermediate range of friction coefficients, reducing the wavenumber leads to the vanishing of the sound peak at a finite frequency and the formation of a maximum at zero frequency. This is in contrast to simulations without friction, where the characteristic Rayleigh and Brillouin peaks are observed. The Rayleigh peak around zero frequency for systems without dissipation is generally weak. The simulations show that a small amount of friction can initially decrease its height even further before a strong single maximum is formed at strong damping. At large wavenumbers, the DSF of moderately coupled Yukawa plasmas with dissipation is well described by a single-particle model without interactions, provided frictional damping is taken into account. [ABSTRACT FROM AUTHOR]