A5062780586- Diamond and Carbon-based Materials Research
- 2D Materials and Applications
- Graphene research and applications
- High-pressure geophysics and materials
- Electronic and Structural Properties of Oxides
- Spectroscopy and Quantum Chemical Studies
- Semiconductor materials and devices
- Advanced Chemical Physics Studies
- Solid-state spectroscopy and crystallography
- Boron and Carbon Nanomaterials Research
- Magnetic and transport properties of perovskites and related materials
- Topological Materials and Phenomena
- Metal and Thin Film Mechanics
- Advanced Condensed Matter Physics
- Chalcogenide Semiconductor Thin Films
- Strong Light-Matter Interactions
- Perovskite Materials and Applications
- GaN-based semiconductor devices and materials
- Force Microscopy Techniques and Applications
- MXene and MAX Phase Materials
- Silicon Carbide Semiconductor Technologies
- Ga2O3 and related materials
- Advanced Physical and Chemical Molecular Interactions
- Semiconductor Quantum Structures and Devices
- Advanced Mathematical Modeling in Engineering
Physique des interactions ioniques et moléculaires
2015-2024
Aix-Marseille Université
2015-2024
European Theoretical Spectroscopy Facility
2017-2023
Centre National de la Recherche Scientifique
2015-2022
University of Rome Tor Vergata
2008-2020
University of Tabriz
2019
Institut Laue-Langevin
2013-2017
Délégation Provence et Corse
2015
University of the Basque Country
2011-2012
Material Physics Center
2012
yambo is an open source project aimed at studying excited state properties of condensed matter systems from first principles using many-body methods. As input, requires ground electronic structure data as computed by density functional theory codes such Quantum ESPRESSO and Abinit. yambo's capabilities include the calculation linear response quantities (both independent-particle including electron-hole interactions), quasi-particle corrections based on GW formalism, optical absorption, other...
Strong in-plane bonding and weak van der Waals interplanar interactions characterize a large number of layered materials, as epitomized by graphite. The advent graphene (G), individual layers from graphite, atomic isolated few other bonded compounds has enabled the ability to pick, place, stack arbitrary compositions build unique which would be otherwise impossible synthesize via known techniques. Here we demonstrate this concept for solids consisting randomly stacked hexagonal boron nitride...
The quantum zero-point motion of the carbon atoms is shown to induce strong effects on optical and electronic properties diamond trans-polyacetylene, a conjugated polymer. By using an ab initio approach, we interpret subgap states experimentally observed in terms entangled electron-phonon states. These also appear trans-polyacetylene causing formation structures band structure that even call into question accuracy theory. This imposes critical revision results obtained for carbon-based...
We study the luminescence of hexagonal boron nitride $(h\text{\ensuremath{-}}\mathrm{BN})$ by means nonequilibrium Green's functions plus finite-difference electron-phonon coupling. derive a formula for light emission in solids limit weak excitation that includes perturbatively contribution coupling at first order. This is applied to bulk $h\text{\ensuremath{-}}\mathrm{BN}$. material has attracted interest due its strong ultraviolet region electromagnetic spectrum [K. Watanabe et al., Nat....
The second harmonic generation (SHG) intensity spectrum of SiC, ZnO, GaN two-dimensional hexagonal crystals is calculated by using a real-time first-principles approach based on Green's function theory [Attaccalite et al., Phys. Rev. B: Condens. Matter Mater. 2013 88, 235113]. This allows one to go beyond the independent particle description used in standard nonlinear optics calculations including quasiparticle corrections (by means GW approximation), crystal local field effects and...
We report here the discovery of multiferroicity and large magnetoelectric coupling in type I orbital order system GeV₄S₈. Our study demonstrates that this clustered compound displays a para-ferroelectric transition at 32 K. This originates from an ordering which reorganizes charge within metal clusters. Below antiferromagnetic 17 K, application magnetic field significantly affects ferroelectric polarization, revealing thus coupling. suggests induces metamagnetic polarization thanks to...
Abstract The development of theories and methods devoted to the accurate calculation electronic quasi-particle states levels molecules, clusters solids is prime importance interpret experimental data. These quantum systems are often modelled by using Born–Oppenheimer approximation where coupling between electrons vibrational modes not fully taken into account, treated as pure quasi-particles. Here, we show that in small diamond cages, called diamondoids, electron–vibration leads breakdown...
We combine the effect of electron-electron and electron-phonon interactions to study electronic optical properties $zb$-GaN. show that only by treating two effects at same time is it possible obtain an unprecedented agreement zero- finite-temperature gaps absorption spectra with experimental results. Compared state-of-the-art results our calculations predict a large on main peak position width as well overall line shape. These important modifications are traced back combined damping...
The accuracy of the many-body perturbation theory $GW$ formalism to calculate electron-phonon coupling matrix elements has been recently demonstrated in case a few important systems. However, related computational costs are high and thus represent strong limitations its widespread application. In present study, we explore two less demanding alternatives for calculation on level. Namely, test static Coulomb-hole plus screened-exchange (COHSEX) approximation further constant screening...
Second harmonic generation (SHG) of single-layer monochalcogenides, such as GaSe and InSe, has been recently reported [2D Mater. 5, 025019 (2018); J. Am. Chem. Soc. 137, 7994 (2015)] to be extremely strong with respect bulk multilayer forms. To clarify the origin this SHG signal, we perform first-principles real-time simulations linear nonlinear optical properties these two-dimensional semiconducting materials. The simulations, based on ab initio many-body theory, accurately treat...
Linear and nonlinear optical properties of low dimensional nanostructures have attracted a large interest in the scientific community as tools to probe strong confinement electrons for possible applications optoelectronic devices. In particular it has been shown that linear response carbon nanotubes [Science 308, 838 (2005)] graphene nanoribbons [Nat. Comm. 5, 4253 (2014)] is dominated by bounded electron-hole pairs, excitons. The role excitons widely studied, but still little known on their...
Abstract By means of ab initio band structure methods and model Hamiltonians we investigate the electronic, spin topological properties four monopnictides crystallizing in bct structure. We show that Weyl bands around a WP W1 or W2 possess strong anisotropy tilt accompanying Dirac cones. These effects are larger for nodes than ones. The node tilts positions energy space significantly influence DOS single-particle excitations. anisotropies destroy conventional picture (anti)parallel wave...
The lattice dynamics of the GeV4S8 compound has been investigated using both density functional calculations and Raman/infrared (IR) measurements. While accordance between computed experimental data is very good in low-temperature, ferroelectric phase (25K, Imm2), this not case for high-temperature, paraelectric one within F4̅3m group. Using group theory first-principles calculations, we show that IR/Raman phonon modes are, however, compatible with I4̅m2 space Analysis different at...
Electronic properties and lattice dynamics of bulk $\varepsilon$-GaSe mono-, bi- tri-tetralayer GaSe are investigated by means density functional perturbation theory. The few-tetralayers systems semiconductors with an indirect nature the fundamental band gap a Mexican-hat-shape is observed at top valence band. phonon branches analysis reveals dynamical stability for all considered together LO-TO splitting breakdown in two-dimensional systems. In-plane (E) out-of-plane (A) zone-center...
In this paper we investigate from first principles the effect of electron-phonon interaction in two paradigmatic nanostructures: trans-polyacetylene and polyethylene. We found that strong leads to appearance complex structures frequency dependent electronic self-energy. Those rule out any quasi-particle picture, make adiabatic static approximations commonly used well-established Heine Allen Cardona (HAC) approach inadequate. propose, instead, a fully ab-initio dynamical formulation problem...
Wurtzite Boron Nitride ($w\mathrm{BN}$) is a wide band gap BN polymorph with unique mechanical properties such as hardness and stiffness. Initially synthesized in 1963 by transforming hexagonal ($h\mathrm{BN}$) under high temperature pressure conditions, $w\mathrm{BN}$ can now be stabilized at atmospheric to obtain high-quality samples. Our first-principles study investigates the electronic, vibrational, optical of across broad range pressures. We account for electron-hole interaction...
By means of $ab \ initio$ band structure methods and model Hamiltonians we investigate the electronic, spin topological properties four monopnictides crystallizing in body centered tetragonal structure. We show that Weyl bands around a point W1 or W2 possess strong anisotropy tilt accompanying Dirac cones. These effects are larger for nodes than ones. The node tilts positions energy space significantly influence density states single-particle excitations. anisotropies destroy conventional...
We present a detailed study of the electronic properties and lattice dynamics bulk mono-, bi- tri-tetralayer \ensuremath{\beta}-InSe by means density functional perturbation theory. show that few-layers systems are semiconductors with an indirect nature fundamental band gap Mexican-hat-shape top valence band. The phonon branches analysis reveals dynamical stability mono- bi-tetralayer considered together longitudinal-optical--transverse-optical splitting breakdown toward one tetralayer....
Abstract We review the theoretical framework of ab‐initio excited state properties calculations showing application these methods to systems different dimensionality. Many body perturbation theory within GW approximation self energy for calculation electronic band structures is presented and applied liquid water. The Bethe Salpeter equation computation optical illustrated used case surfaces An alternativemethod properties, Time Dependent Density Functional Theory, also briefly illustrated....
Direct observation of temperature dependence individual bands semiconductors for a wide region is not straightforward, in particular. However, this fundamental property prerequisite understanding the electron-phonon coupling semiconductors. Here we apply ab initio many-body perturbation theory to on hexagonal silicon carbide (SiC) crystals and determine bands. We find significant renormalization band gap at 0 K. Both conduction valence shift elevated temperatures, exhibiting different...
Nonlinear optical frequency conversion, where fields interact with a nonlinear medium to generate new frequencies, is key phenomenon in modern photonic systems. However, major challenge these techniques lies on the difficulty of tuning electrical susceptibilities that drive such effects given material. As result, dynamic control nonlinearities has remained largely confined research laboratories, limiting its practical use as spectroscopic tool. In this work, we aim advance development...