Plasmons and polar phonons are elementary electrodynamic excitations of matter. In 2d and at long wavelengths, they couple to light and act as the system polaritons. They also dictate the scattering of charged carriers. Van der Waals heterostructures offer the opportunity to couple excitations from different layers via long-range Coulomb interactions, modifying both their dispersion and their scattering of electrons. Even when the excitations do not couple, they are still influenced by the screening from all layers, leading to complex dynamical interactions between electrons, plasmons and polar phonons. We develop an efficient ab initio model to solve the dynamical electric response of Van der Waals heterostructures, accompanied by a formalism to extract relevant spectroscopic and transport quantities. Notably, we obtain scattering rates for electrons of the heterostructure coupling remotely with electrodynamic excitations. We apply those developments to BN-capped graphene, in which polar phonons from BN couple to plasmons in graphene. We study the nature of the coupled excitations, their dispersion and their coupling to graphene's electrons. Regimes driven by either phonons or plasmons are identified, as well as a truly hybrid regime corresponding to the plasmon-phonon-polariton at long wavelengths. Those are studied as a function of the graphene's Fermi level and the number of BN layers. In contrast with standard descriptions in terms of surface-optical phonons, we find that the electron-phonon interaction stems from several different modes. Moreover, the dynamical screening of the coupling between BN's LO phonons and graphene's electrons crosses over from inefficient to metal-like depending on the relative value of the phonons' frequency and the energetic onset of interband transitions. While the coupling is significant in general, the associated scattering of graphene's carriers is found to be negligible in the context of electronic transport.

In this article we present a comprehensive study of the totally asymmetric simple exclusion process with pausing particles (pTASEP), a model initially introduced to describe RNAP dynamics during transcription. We extend previous mean-field approaches and demonstrate that the pTASEP is equivalent to the exclusion process with dynamical defects (ddTASEP), thus broadening the scope of our investigation to a larger class of problems related to transcription and translation. We extend the mean-field theory to the open boundary case, revealing the system's phase diagram and critical values of entry and exit rates. However, we identify a significant discrepancy between theory and simulations in a region of the parameter space, indicating severe finite-size effects. To address this, we develop a single-cluster approximation that captures the relationship between current and lattice size, providing a more accurate representation of the system's dynamics. Finally, we extend our approach to open boundary conditions, demonstrating its applicability in different scenarios. Our findings underscore the importance of considering finite-size effects, often overlooked in the literature, when modelling biological processes such as transcription and translation.

2D materials have shown fascinating fundamental physics as well as exciting technological prospects, from transistors to integrated optoelectronics. Many applications rely on the ability of the 2D material to conduct electrons efficiently. At room temperature, this is mostly limited by the scattering of electrons by phonons. A clear understanding of the electronic transport mechanisms, along with predictive ab initio simulations, are then key to design performant and energy-efficient devices. In this framework, 2D materials present 3 major peculiarities: their reduced dimensionality, the ability to taylor their properties by combining different layers in a van der Waals heterostructure, and the ubiquitous usage of electrostatic doping. The latter refers to the field-effect transistor configuration, in which a gate is used to induce charges in the 2D material and change its Fermi level.We will explore the consequences of those 3 peculiarities on electron-phonon interactions and the scattering mechanisms. We will see how to compute the macroscopic quantities characterising the transport of electrons through the material, and discuss the performances of various layers taken from a database of exfoliable 2D materials build with high-throughput ab initio workflows.

In order to explore the structural mechanisms responsible for the plastic behavior andpolyamorphism in silica glasses v-SiO2, we have performed Molecular Dynamics (MD)simulations using different approaches. Recently, a Density Functional Tight-Binding(DFTB) (1) study has shown that the structural changes from low- to high-densityamorphous structures in v-SiO2 occur through a sequence of percolation transitions (2).These transitions also explain some of the mechanical properties of v-SiO2.To gain a deeper insight into the properties of the clusters and percolations networks, wehave performed classical MD simulations using a reliable pair potential (3). Due to its lowcomputational load, this method has allowed us to significantly increase the size of thesimulated system and have access to large length scales, from 2.5 to 12.0 nm. Similarpercolation transitions have been identified also for these new models. Generating severalorders of magnitude of cluster sizes allows the extraction of scaling laws associated witheach property of the clusters such as mass, correlation length, order parameter etc... Thescaling of such properties is correlated to the critical exponents or the fractal dimensionalityof the clusters. The collection of these quantities related to the transitions for the differentconnectivities SiO4-SiO4, SiO5-SiO5, SiO6-SiO6 and SiO6-stishovite, leads to thecharacterization of the percolation model, providing compelling evidence for amorphous-amorphous “phase” transitions in compressed silica glasses.

As humans, we interact both visually and sterically when densely surrounded by a crowd. While our steric interactions might be reciprocal, our visual perceptions are not, as they strongly depend on the orientation of our eyes. Inspired by this, we consider a minimal model where the sole effect of visual perception is to modulate the steric potential of particles. Because self-propulsion is absent, this creates backward-moving particles, as they feel more repelled by frontal neighbors than by those behind them. We further simplify by fixing the particle orientations, initially uniformly sampled, and we ignore thermal fluctuations, meaning the particle dynamics is fully deterministic. Despite the simplicity of the model, the emerging collective phenomena at high densities are rich, ranging from crowd-defeating independent backward gliders (at high non-reciprocity) to chaotic collective motion (at intermediate non-reciprocity) that finally terminates in an absorbing phase transition (at small non-reciprocity).

The emergence of surprising collective behaviors in systems driven out of equilibrium by local energy injection at the particle level remains a central theme in the study of active matter. Recently, chaotic flows reminiscent of turbulence have garnered significant attention due to their appearance in diverse biological and physical active matter systems. In this talk, I will demonstrate how even the simplest model of active particles — self-propelled point particles — can exhibit mesoscale flows, characterized by streams and vortices, when very persistent active forces compete with crowding at high densities.In the second part, I will introduce a minimal model of non-reciprocal interactions inspired by human crowds, which generates collective flows strikingly similar to those of the self-propelled particles. Interestingly, as the system approaches the equilibrium limit by reducing non-reciprocity, it undergoes an absorbing phase transition characterized by an infinite number of absorbing states and critical exponents consistent with the conserved directed percolation universality class.