Ab initio molecular dynamics in a finite homogeneous electric field

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Pixelated differential phase contrast (DPC) is a four-dimensional scanning transmission electron microscopy (4D-STEM) technique in which the position of the transmitted beam is tracked to reconstruct the electromagnetic fields of a sample. Although it can provide (semi-) quantitative information for a range of different applications, the measurements are greatly affected by the microscope's optical and acquisition settings in terms of sensitivity, accuracy, and spatial resolution, particularly when measurin

Complex lead-based perovskites with the general formula Pb(Bx'B1-x")O3, represent an important class of antiferroelectrics beyond the prototypical PbZrO3 and NaNbO3. Depending on the combination of B-site species and the degree of cationic ordering, these materials exhibit a wide range of ferroic behaviors, spanning from antiferroelectric to (relaxor) ferroelectric responses. In this study, we investigate (Pb1-xBax)(Yb1/2Nb1/2)O3 polycrystals synthesized via a two-step processing route. Despite displaying a

This study presents a detailed investigation of a nanosecond-pulsed volume dielectric barrier discharge (VDBD) plasma in saturated humid air at atmospheric pressure, combining experimental diagnostics with kinetic modeling. Electric field-induced second harmonic generation (EFISH), employing a spatial filter and a picosecond laser, enabled electric field measurements with high spatial (270 µm) and temporal (28 ps) resolution at three distinct positions across the inter-electrode VDBD gap. These measurements

Understanding how the path of streamers is influenced by background electric fields is crucial in leader progression models and electrical breakdown models in long gaps. While numerous advanced models of streamers exist, applying them to leader progression models to track streamer movement remains computationally intensive and impractical. In this study, we employ one of the simplest streamer models available in the literature to investigate how streamers are deflected in the presence of background electric

Transition metal dichalcogenides (TMDs) are semiconductor Van der Waals materials that can be obtained as stable monolayers (ML), characterized by bandgap values from visible to near infrared range. With decreasing thickness from bulk to MLs, TMDs show a transition from indirect to direct bandgap, which combined to strong exciton binding energies makes them propitious for optoelectronic applications. Their atomically flat, dangling bond free surfaces and weak interlayer van der Waals bonding enable stable e

Dielectric Elastomer Actuators (DEAs) have a wide range of applications. They can be widely used in research to study cells under mechanical movement or stress. This is done by culturing the cells in vitro on the DEA and observing, under the microscope, the morphological and the numerous other important changes they are experiencing. However, in order to make sure that the effects observed on the cells are in fact from the mechanical stimuli alone, no other factors should be influencing the cells. Therefore

The development and implementation of increasingly accurate methods for electronic structure calculations mean that, for many atomistic simulation problems, treating light nuclei as classical particles is now one of the most serious approximations. Even though recent developments have significantly reduced the overhead for modeling the quantum nature of the nuclei, the cost is still prohibitive when combined with advanced electronic structure methods. Here we present how multiple time step integrators can b

We present the successful operation of the first dielectric elastomer actuator (DEA) driven tunable millimeter-wave phase shifter. The development of dynamically reconfigurable microwave/millimeter-wave (MW/MMW) antenna devices is becoming a prime need in the field of telecommunications and sensing. The real time updating of antenna characteristics such as coverage or operation frequency is particularly desired. However, in many circumstances currently available technologies suffer from high EM losses, incr

Strain response of polycrystalline barium titanate (BaTiO3) was investigated under high unipolar electric field (0 to 4 kV/mm) and compressive stress (0 to 400 MPa) in the temperature range from 25 to 160 degrees C. In the vicinity of the Curie point (T-C), nonlinear and hysteretic strain-electric field and strain-stress constitutive behaviors were observed, persisting above T-C where they correspond to the well-known electric field induced double loop polarization behavior. Analogous to the electrical doub

The drift length Ldrift=μτE within the i layer of a-Si:H solar cells is a crucial parameter for charge collection and efficiency. It is strongly reduced not only by light-induced reduction of μτ, but also by electric field deformation ΔE by charges near the p–i and i–n interfaces. Here, a simple model is presented to estimate contributions of free carriers, charges trapped in band tails and charged dangling bonds to ΔE. It is shown that the model reproduces correctly trends observed experimentally and by AS

The L-3 X-ray absorption spectrum of aqueous iodide is reported, and its EXAFS is compared to theoretical spectra reconstructed from the radial distribution function of the iodide hydration obtained from classical, hybrid Quantum Mechanics Molecular Mechanics, (QM/MM) and full quantum (density functional theory, DFT) molecular dynamics simulations. Since EXAFS is mainly sensitive to short distances around the iodide ion, it is a direct probe of the local solvation structure. The comparison shows that QM/MM

We carried out an ab initio molecular dynamics simulation of liquid hydrogen. chloride (l-HCl) at a temperature of 313 K. Comparison with inelastic neutron scattering data shows that the simulation achieves an overall good description of the structural correlations, improving significantly upon a description based on classical interaction potentials. Despite some minor differences between theory and experiment in the H-H partial structure factor, the simulation gives a description of the hydrogen bonding in

We review the structural, electronic and dielectric properties of atomistic models of the Si(100)-SiO2 interface, which have been purposely designed in order to match a large variety of atomic-scale experimental data. After describing the generation procedure and the structural properties of two specific interface models, we study the corresponding electronic structure and dielectric response within the framework of density-functional theory. Particular emphasis is given to a systematic comparison between t

Using density functional theory, we investigate the structural, vibrational, and dielectric properties of titanium oxides and silicates, which have attracted considerable attention in the framework of the quest for alternative high-K materials. For the oxides,. three crystalline phases of titanium dioxide are considered. The first two are hypothetical; they are obtained by similarity with the cubic and tetragonal structure of zirconia ZrO2 or hafnia HfO2. The third is the rutile, a crystal that occurs natur

Recently, engineering return stroke models were extended to take into account the presence of an elevated strike object, which was modeled as an ideal uniform transmission line. We show in this paper that the current distribution associated with these extended models exhibits a discontinuity at the return stroke wave front, which cannot be considered to be physically plausible. This discontinuity arises from the fact that the current injected into the tower from its top is reflected back and forth at its en

The effect of 1 MeV ion implantation on leakage conduction, dielectric and ferroelectric properties of the Pt/Pb(ZrxTi1-x)(2)O-3/Pt capacitors is studied for a wide range of implantation doses (10(10)-10(16) cm(-2)). It is shown that the implantation of Pt+, with an implant and vacancy profile peaking at the bottom interface and a dose within the range of 10(13)-10(16) cm(-2), provokes a strong suppression of the leakage conduction and ferroelectric hysteresis. In addition, ion implantation results in a dec

The contribution of domain walls to the dielectric permittivity of ferroelectrics is customarily explained by the model of locally pinned walls. Here we analyze the complementary case and calculate wall contribution to permittivity of a sample in which 180 degrees domain walls are not pinned locally, moving freely between, "stoppers" representing lattice defects or neighbouring walls. Amplitude dependences and dispersion curves have been calculated for two laws for wall velocity. The model may be pertinent

The postresonator method proposed by Hakki and Coleman for the measurement of dielectric properties of solids in the microwave region is reexamined. Based on the experiments performed around 10 GHz, the limitations of the method in loss determination for materials with tan delta < 5 x 10(-4) are outlined. Alternative techniques for studying high-Q materials are described. Loss measurements performed on well-prepared ceramics have been used to draw comparisons among these techniques. Some of the experimental

Dielectric properties of perovskites are studied both to gain insight into fundamental aspects of the freezing of polar disorder, and to investigate their technological potential. The dynamics of freezing of polar disorder is investigated in single crystals of Li-doped potassium tantalate (K1-xLixTaO3) and lead magnesium niobate (pb[Mg1/3Nb2/3]O3). For the mixed crystal K1-xLixTaO3, the dielectric permittivity ε (ω) is measured at various temperatures and for frequencies ω/2π ranging from 2 × 10-4 to 109 Hz

The temperature coefficient of the dielectric permittivity (tau(epsilon)) of nonferroelectric complex perovskites is of importance in the application of these cermaics to microwave filters and resonators. Recent work has directly related changes in the tau(epsilon) of complex perovskites to the onset of structural phase transitions which involve tilting of the octahedra. It can be argued that the onset of octahedral tilting is controlled by the tolerance factor (t). Thus, a relationship between tau(epsilon)

Ab initio molecular dynamics in a finite homogeneous electric field

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Assessing the electric field sensitivity measured by pixelated differential phase contrast imaging in vacuum both in the absence of external fields and under field-bound conditions

Temperature-dependent field-induced phase transition behavior in Pb(Yb1/2Nb1/2)O3-based antiferroelectrics

Nanosecond-pulsed volume DBD plasma in saturated humid air: a combined experimental and computational study using EFISH and LIF

Deflection of Electric Streamer Channels in an Applied Electric Field

Engineering GaAs nanostructures for heterointegration with 2D transition metal dichalcogenides

Implementation of an Electrostatic Device for Investigation of Electric Fields on Cells

Accurate molecular dynamics and nuclear quantum effects at low cost by multiple steps in real and imaginary time: Using density functional theory to accelerate wavefunction methods

A tunable millimeter-wave phase shifter driven by dielectric elastomer actuators

Critical mechanical and electrical transition behavior of BaTiO3: The observation of mechanical double loop behavior

Charge collection in amorphous silicon solar cells: Cell analysis and simulation of high-efficiency pin devices

The solvent shell structure of aqueous iodide: X-ray absorption spectroscopy and classical, hybrid QM/MM and full quantum molecular dynamics simulations

Ab initio molecular dynamics of liquid hydrogen chloride

Atomistic models of the Si(100)-SiO2 interface: structural, electronic and dielectric properties

Titanium oxides and silicates as high-kappa dielectrics: A first-principles investigation

Electromagnetic field radiated by lightning to tall towers: treatment of the discontinuity at the return stroke wave front

Pt-ion-implantation-induced suppression of leakage conduction in Pt/Pb(ZrxTi1-x)O-3/Pt capacitors

Permittivity enhancement due to domain walls interacting with repulsive defects

Dielectric measurements on high-Q ceramics in the microwave region

Dielectric properties of perovskites with polar disorder (K1-xLix TaO3 and Pb[Mg1/3Nb2/3]O3) and of SrTiO3 films

Dielectric and Structural Characteristics of Ba-Based and Sr-Based Complex Perovskites as a Function of Tolerance Factor