The origin of beam disparity in emittance and betatron oscillation orbits, out the polarization plane drive laser laser-plasma accelerators, is explained terms oscillations driven by field. As trapped electrons accelerate, they move forward interact with pulse. For bubble regime, a simple model presented to describe this interaction harmonic oscillator driving force from restoring plasma wake resulting plane, period approximately wavelength laser, increase that cause microbunching beam....

The feasibility of synthesizing functionalized h-BN (FBN)<italic>via</italic>the reaction between molten LiOH and solid is studied for the first time its ever application as an electrode material in Li-ion batteries evaluated.

The triggering of wave-breaking in a three-dimensional laser plasma wake (bubble) is investigated. Coulomb potential from nanowire used to disturb the field initialize wave-breaking. electron acceleration becomes more stable and power needed for self-trapping lowered. Three-dimensional particle-in-cell simulations were performed. Electrons with charge about 100pC can be accelerated stably energy 170MeV 460mJ. first step towards tailoring beam properties such as energy, spread, discussed.

This paper presents a new approach to the linear scaling evaluation of density matrices in electronic structure theory. The is based on iterative computation special matrix function, sign and its performance compared that some other methods developed for similar purpose. One particular variant turned out be very competitive with algorithms, terms computational time accuracy. It also shown damping technique greatly improves stability self-consistent field (SCF) calculations when using...

We report how ultrathin MgO films on Ag(001) surfaces can be used to control the emittance properties of photocathodes. In addition substantially reducing work function metal surface, layers also favorably influence shape surface bands resulting in generation high-brightness electron beams. As number varies from 0 3, emitted beam becomes gradually brighter, its transverse 0.06 mm mrad. suggest use such photocathodes for development free-electron x-ray lasers and energy-recovery linac sources.

The interface between highly oriented pyrolytic graphite (HOPG) and 1-butyl-3-metyl-imidazolium hexafluorophosphate (BMIPF6) has been studied using cyclic voltammetry, electrochemical impedance spectroscopy, immersion charge measurements in situ scanning tunneling microscopy (in STM). results are compared with those obtained Au(100) BMIPF6 (Phys. Chem. Phys., 2011, 13, 11627). main result is that the high frequency capacitance spectra on two systems similar to each other, however at low...

The electronic properties of thiophene oligomers (nT, n=2–8) have been investigated in the lowest excited triplet state. Theoretical calculations zero field splitting parameters and π-electron spin density performed compared with previous experimental EPR results. are based on a simple (one-electron-per-site) model including electron–electron interaction at extended Hubbard level. Optimized bond lengths result from making them self-consistent to corresponding orders via Coulson’s...

The atomic structures, static polarizabilities, and optical absorption spectra of eight low-energy isomers ${\mathrm{Ag}}_{11}$ are investigated from first principles within time-dependent density functional theory. energies all fall a range $\ensuremath{\sim}0.3\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ in width. It is the spectrum lowest-energy isomer that exhibits best overall agreement with available measured spectra. analysis indicates $d$ electrons play an important role excitations...

An approach has been developed for calculating the vibrational spectra of linear methine-bridged tetrapyrroles constituting chromophoric sites various photoreceptor proteins. Using Pulay's scaling procedure (Pulay, P.; Fogarasi, G.; Pongor, Boggs, J. E.; Vargha, A. Am. Chem. Soc. 1983, 105, 7037), factors were determined a set 10 training molecules which mimic structural elements tetrapyrrole target molecules. Geometries and force fields calculated at three theoretical levels, i.e., by...

An efficient implementation of simultaneous reverse Monte Carlo (RMC) modeling pair distribution function (PDF) and EXAFS spectra is reported. This an extension the technique established by Krayzman et al. [J. Appl. Cryst. 42, 867 (2009)] in sense that it enables real-space fitting x-ray PDF with accurate treatment Q-dependence scattering cross-sections multiple photoelectron included. The also allows for atom swaps during fits thereby enabling effects chemical disorder, such as migrating...

We present theoretical analysis on why and how rechargeable metal-air type batteries can be made significantly safer more practical by utilizing CO2/oxalate conversions instead of O2/peroxide or O2/hydroxide ones, in the positive electrode. Metal-air batteries, such as Li-air one, may have very large energy densities, comparable to that gasoline, theoretically allowing for long range all-electric vehicles. There are, however, still significant challenges, especially related safety their...

This article presents a new algorithm to solve the coordinate transformation problem of molecular geometry optimization. The is very fast and its CPU time consumption scales linearly with system size. It makes use locality internal coordinates by efficient sparse matrix techniques. drastically reduces needed for transformations as demonstrated test calculations on polyalanine carbone nanotube systems: 2000 atom it requires just seven seconds, instead hours consumed traditional schemes.

The resonance Raman (RR) spectra of monomeric 3,3',4,4',5,5'-hexamethylpyrromethene (HMPM) were measured upon excitation in with the strong 436 nm absorption band. experimental analyzed by comparison calculated RR that obtained on basis scaled quantum chemical force fields combination transform theory. ground-state structure and field HMPM density functional theory (DFT) using B3LYP exchange 6-31G* set. adopts a planar contrast to dimers which intermolecular hydrogen-bonding interactions...

Anomalous anisotropy of work function values in ternary alkali metal transition acetylides is reported. Work some characteristic surfaces these emerging semiconducting materials may differ by more than 2 eV as predicted density functional theory calculations. This large a consequence the relative orientation rodlike [MC${}_{2}$]${}_{\ensuremath{\infty}}$ negatively charged polymeric subunits and surfaces, with M being or metalloid element C${}_{2}$ refers to acetylide ion...

Ultrahigh energy density batteries based on α-LixBN2 (1 ⩽ x 3) positive electrode materials are predicted using functional theory calculations. The utilization of the reversible LiBN2 + 2 Li+ e− \documentclass[12pt]{minimal}\begin{document}$\rightleftharpoons$\end{document}⇌ Li3BN2 electrochemical cell reaction leads to a voltage 3.62 V (vs Li/Li+), theoretical densities 3251 Wh/kg and 5927 Wh/l, with capacities 899 mAh/g 1638 mAh/cm3, while volume α-Li3BN2 shrinks only 2.8% per two-electron...

We use angle-resolved photoemission under ultraviolet laser excitation to demonstrate that the electron emission properties of Ag(001) can be markedly enhanced and redirected along surface normal by deposition a few monolayers epitaxial MgO. observe new low-binding energy states with small spreads in their parallel momenta as result MgO/Ag(001) interface formation. Under 4.66 eV excitation, quantum efficiency is factor 7 greater than clean Ag(001), revealing utility such heterojunctions...

Several effective methods have been developed recently to demonstrate simultaneous high energy and power density in Lithium - carbon fluoride (Li-CFx) batteries. These can achieve as a 1000 Wh/kg at 60–70 kW/kg (40–50 C rate) coin cells 750 12.5 (20 pouch cells. This performance is made possible by an ingenious nano-architecture design, controlled porosity, boron doping, electrolyte additives. In the present study, we show that similarly great performance, 931 59 density, be achieved using...

A theoretical study on the energetics and structures of lowest triplets C60, C70, C76, C78, C82, C84 is reported. Excited state geometries, excitation phosphorescence energies, as well Jahn−Teller distortions for degenerate levels were determined. Zero-field splittings various evaluated; signs magnitudes resulting D E parameters are quite sensitive to system symmetry particular excited state. Atomic spin density distributions determined triplet states.

The structure and vibrational spectra of hexamethylpyrromethene (HMPM) have been investigated by X-ray crystallography, IR Raman spectroscopies, density functional theory calculations. HMPM crystallizes in the form dimers, which are held together bifurcated N-H(...N)(2) hydrogen bonds, involving one intramolecular intermolecular N-H...N interaction. monomers essentially planar, mean planes lie approximately perpendicular to another, so that four N atoms dimer a distorted tetrahedron. is...