A5073729426- 2D Materials and Applications
- Chalcogenide Semiconductor Thin Films
- Perovskite Materials and Applications
- Graphene research and applications
- Semiconductor Quantum Structures and Devices
- Advanced Electron Microscopy Techniques and Applications
- Liquid Crystal Research Advancements
- Thermal properties of materials
- Quantum and electron transport phenomena
- Boron and Carbon Nanomaterials Research
- Solid-state spectroscopy and crystallography
- Organic and Molecular Conductors Research
- Machine Learning in Materials Science
- Photonic Crystals and Applications
- Plasmonic and Surface Plasmon Research
- Electronic Packaging and Soldering Technologies
- Phase-change materials and chalcogenides
- Thermal Expansion and Ionic Conductivity
- Plant Reproductive Biology
- Diamond and Carbon-based Materials Research
- Advanced Chemical Physics Studies
- Quantum, superfluid, helium dynamics
- Shape Memory Alloy Transformations
- MXene and MAX Phase Materials
- Advanced Thermoelectric Materials and Devices
UES (United States)
2021-2024
Wright-Patterson Air Force Base
2021-2024
University of Liège
2013-2022
United States Air Force Research Laboratory
2022
European Theoretical Spectroscopy Facility
2017-2022
University of Oslo
2018-2022
The Ohio State University
2013-2017
abinit is probably the first electronic-structure package to have been released under an open-source license about 20 years ago. It implements density functional theory, density-functional perturbation theory (DFPT), many-body (GW approximation and Bethe–Salpeter equation), more specific or advanced formalisms, such as dynamical mean-field (DMFT) “temperature-dependent effective potential” approach for anharmonic effects. Relying on planewaves representation of wavefunctions, density, other...
The direct manipulation of individual atoms in materials using scanning probe microscopy has been a seminal achievement nanotechnology. Recent advances imaging resolution and sample stability have made transmission electron promising alternative for single-atom covalently bound materials. Pioneering experiments an atomically focused beam demonstrated the directed movement silicon over handful sites within graphene lattice. Here, we achieve much greater degree control, allowing us to...
We investigate the chemical bonding characteristics of transition metal dichalcogenides based on their static and dynamical atomic charges within Density Functional Theory. The trigonal are anomalously large, while in hexagonal counterparts, sign is even counterintuitive i.e. takes negative charge. This phenomenon cannot be understood simply terms a change charge as it results from local polarization. present our theoretical understanding these phenomena perturbative response system to...
Indium selenide (InSe) multilayers have attracted much interest recently due to their electronic and optical properties, partially dependent on the existence of an indirect-to-direct bandgap transition that is correlated multilayer thickness. In this work, we investigate stacks van der Waals-bonded InSe, ordered similarly γ phase bulk InSe. We analyze using first-principles methods, identifying structural changes in structures cause modifications result transition. highlight differences...
The second-order nonlinear optical properties of monolayer transition-metal dichalcogenides (TMDs) have been drawing increasing interest; yet, challenges remain in the measurements response. In this work, we report a first-principles analysis response TMDs for transition metals from group V and VI. Our calculations are useful benchmarking, providing intrinsic response, elucidation trends developing concepts application. We analyzed results by comparison with experimental previous...
With advances in the growth of Janus transition metal dichalcogenide (TMD) monolayers and potential applications for materials with a permanent dipole moment, we investigate electronic, linear, second-order nonlinear optical properties TMDs using first-principles calculations. We compare our results to available experimental measurements, finding relatively good agreement. find appearance Rashba spin splitting mixing susceptibility components TMD contrary their monolayer counterparts. While...
In the limit of low adatom concentration, we obtain exact analytic expressions for local and total density states (LDOS, TDOS) a tight-binding model adatoms on graphene. The is not limited to nearest-neighbor hopping but can include between carbon atoms at any separation. We also find an analytical expression spectral function $A(\mathbf{k},E)$ electron Bloch vector $\mathbf{k}$ energy $E$ graphene lattice, first order in concentration. treat electron-electron interaction by including...
Predictions of the anisotropic coefficients thermal expansion are needed to not only compare experimental measurement, but also as input for macroscopic modeling devices which operate over a large temperature range. While most current methods limited isotropic systems within quasiharmonic approximation, our method uses first-principles calculations and includes anharmonic effects determine temperature-dependent properties materials. These include lattice parameters, expansion, isotherm bulk...
Interest in the bulk transition metal dichalcogenides for their electronic, photovoltaic, and optical properties has grown led to use many technological applications. We present a systematic investigation of interlinked vibrational dielectric using density functional theory perturbation theory, studying effects spin-orbit interaction long-range ${e}^{\ensuremath{-}}\phantom{\rule{0.28em}{0ex}}\ensuremath{-}\phantom{\rule{0.28em}{0ex}}{e}^{\ensuremath{-}}$ correlation as part our...
First-principles studies of two-dimensional transition metal dichalcogenides have contributed considerably to the understanding their dielectric, optical, elastic, and vibrational properties. The majority works date focus on a single material or physical property. Here we use first-principles methodology whole family systems, investigate in depth relationships between different properties, underlying symmetry composition these materials, observe trends. We compare bulk counterparts show...
Transmission electron microscopy characterization may damage materials, but an beam can also induce interesting dynamics. Elastic knock-on is the main irradiation mechanism in metals including graphene, and although atomic vibrations influence its cross section, only out-of-plane direction has been considered so far. Here, we present a full three-dimensional first-principles theory of displacements effect temperature on to describe dynamics into arbitrary directions. We validate model with...
Stacks of nanostructured 2D materials can display properties distinct from those the parent materials. In heterostructures transition metal dichalcogenides, authors find here that dissimilar chalcogen species induce a spontaneous compression van der Waals gap. This is result induced charge displacement within and between layers, which modifies out-of-plane polarizability, stabilize density waves or ferroelectricity. The hope to stimulate experimental investigation tunability in mixed systems.
A chain of metallic particles, sufficiently small diameter and spacing, allows linearly polarized plasmonic waves to propagate along the chain. In this paper, we consider how these are altered by an anisotropic host (such as a nematic liquid crystal) or applied magnetic field. crystalline host, with principal axis (director) oriented either parallel perpendicular chain, find that dispersion relations both longitudinal ($L$) transverse ($T$) modes significantly relative those isotropic host....
We show that, in graphene with a small concentration of adatoms, the total magnetic moment μT can be switched on and off by varying Fermi energy EF, either applying gate voltage or suitable chemical doping. Our calculation is carried out using simple tight-binding model described previously, combined mean-field treatment electron-electron interaction adatom. The values EF at which turned are controlled strength hopping between sheet adatom, on-site correlation U. result qualitatively...
The doping of wide band-gap semiconducting ZnSe by transition metal (TM) atoms finds applications from mid-infrared lasing, sensing, photoelectrochemical cells, to nonlinear optics. Yet understanding the response these materials at atomic and electronic level is lacking, particularly in comparing a range TM dopants, which were studied primarily phenomenological crystal-field theory. In this work, investigate bulk singly doped with first-row atoms, specifically Ti through Cu, we applied...
We develop a simple theory for the spin-dependent Seebeck effect in $n$-doped InSb an external magnetic field. consider spin-$1/2$ electrons conduction band of with temperature gradient parallel to applied In absence spin-orbit interactions, Boltzmann equation approach leads spin current field and proportional gradient. The calculated coefficient oscillates as function $B$; peak positions are approximately periodic $1/B$. oscillations arise when Fermi energy crosses bottom Landau band.
We calculate the dispersion relations of plasmonic waves propagating along a chain semiconducting or metallic nanoparticles in presence both static magnetic field B and liquid crystalline host. The are obtained using quasistatic approximation dipole-dipole to treat interaction between surface plasmons on different nanoparticles. For particle nematic host with director parallel chain, we find small, but finite, Faraday rotation angle. perpendicular still couples longitudinal one two...
Using the quasistatic approximation, we calculate dispersion relations for plasmonic waves along a chain of metallic nanoparticles when host is nematic or cholesteric liquid crystal (NLC CLC). If director NLC perpendicular to chain, doubly degenerate transverse (T) branches split into two linearly polarized branches. For CLC with twist axis parallel T again split, but are no longer polarized. We illustrate these results numerically by calculating Drude metal particles in either an CLC.
The Cu-Pd-Sn material system has a (Cu, Pd)3Sn phase region that shows an interesting and unexplored martensitic transformation. Literature on this is limited the description of phases present incomplete partly contradictory. With focus specific Cu-rich composition in (Cu33Pd42Sn25) having employed combination differential scanning calorimetry, X-ray diffraction, optical microscopy density functional theory (DFT) methods we analyze involved transformation temperatures. was found to occur at...
Efficient, scalable, and tailorable surface hybridization of layered transition metal dichalcogenides (LTMDs) is crucial to optimize performance enable reproducible, bulk manufacturing technologies (spray coating, inkjet printing, slot-dye etc.) for optoelectronic, energy storage, sensing applications. Group V LTMDs (NbX2, TaX2, VX2, where X = S, Se, Te) provide unique opportunities due their superconductive paramagnetic properties; however, hydrolytic instability challenges colloidal...
Elastic knock-on is the main electron irradiation damage mechanism in metals including graphene. Atomic vibrations influence its cross-section, but only out-of-plane direction has been considered so far literature. Here, we present a full three-dimensional theory of effect temperature and to describe ejection into arbitrary directions. We thus establish general quantitative description effects through elastic scattering. Applying our methodology in-plane jumps pyridinic nitrogen atoms, show...
We calculate the dispersion relations of plasmonic waves propagating along a chain metallic nanoparticles in presence both static magnetic field ${\bf B}$ and liquid crystalline host. The are obtained using quasistatic approximation dipole-dipole to treat interaction between surface plasmons on different nanoparticles. For particle nematic host parallel chain, we find small, but finite, Faraday rotation angle. In cholesteric crystal an applied for left- right-moving found be different. some...