Effects of Molecular Adsorption on Optical Losses of the Ag (111) Surface

The first principles density functional theory (DFT) is applied to study effects of molecular adsorption on optical losses of silver (111) surface. The ground states of the systems including water, methanol, and ethanol molecules adsorbed on Ag (111) surface were obtained by the total energy minimization method within the local density approximation (LDA). Optical functions were calculated within the Random Phase Approximation (RPA) approach. Contribution of the surface states to optical losses was studied by calculations of the dielectric function of bare Ag (111) surface. Substantial modifications of the real and imaginary parts of the dielectric functions spectra in the near infrared and visible spectral regions, caused by surface states and molecular adsorption, were obtained. The results are discussed in comparison with available experimental data.Comment: 7 pages, 4 figures, 1 tabl

Engineering of Low-Loss Metal for Nanoplasmonic and Metamaterials Applications

We have shown that alloying a noble metal (gold) with another metal (cadmium), which can contribute two electrons per atom to a free electron gas, can significantly improve the metals optical properties in certain wavelength ranges and make them worse in the other parts of the spectrum. In particular, in the gold-cadmium alloy we have demonstrated a significant expansion of the spectral range of metallic reflectance to shorter wavelengths. The experimental results and the predictions of the first principles theory demonstrate an opportunity for the improvement and optimization of low-loss metals for nanoplasmonic and metamaterials applications.Comment: 14 Pages, 4 figure

Pressure and temperature driven phase transitions in HgTe quantum wells

We present theoretical investigations of pressure and temperature driven phase transitions in HgTe quantum wells grown on CdTe buffer. Using the 8-band \textbf{k$\cdot$p} Hamiltonian we calculate evolution of energy band structure at different quantum well width with hydrostatic pressure up to 20 kBar and temperature ranging up 300 K. In particular, we show that in addition to temperature, tuning of hydrostatic pressure allows to drive transitions between semimetal, band insulator and topological insulator phases. Our realistic band structure calculations reveal that the band inversion under hydrostatic pressure and temperature may be accompanied by non-local overlapping between conduction and valence bands. The pressure and temperature phase diagrams are presented.Comment: 9 pages, 8 figures + Supplemental material (5 pages

Variative modelling of one-dimensional contours according to the given conditions

Model of the surface of complex shape is usually formed on the basis of the frame, elements of which are plane and spatial curves. The task of ensuring the functional properties of these surfaces requires the development of methods for the formation of linear elements of the model as a one dimensional contours with the desirable law of geometric characteristics change. The order of fixation and order of smoothness of contour, curvature and torsion values which change along the curve are those characteristics for spatial curves

Use of copper phtalocyanine adsorption layer for substraction of spirits in gasochromatographic analysis

The chromatographic properties of silica gel with copper phtalocyanine surface layer are investigated. Parameters of hydrocarbons and oxygen-containing organic substances retention are different for the layers obtained by sorption method and chemical synthesis that is connected with structure of complex on the carrier surface. Sorbents are used to analyse mixtures of oxygen-containing compounds and to subtract spirits at group analysis of oxygen-containing organic substances

Transport of covariance matrices in the inhomogeneous magnetic field of the ATLAS experiment by the application of a semi-analytical method

In this paper we study the transport of track parameter covariance matrices - the so-called error propagation - in the inhomogeneous magnetic field of the ATLAS experiment. The Jacobian elements are transported in parallel with the track parameters, avoiding the inherent need of any purely numerical scheme of propagating a set of auxiliary tracks. We evaluate the quality of the transported Jacobians by a very thorough, purely numerical approach of obtaining the same derivatives, providing a quantitative understanding of the effects of including gradients of energy loss and the magnetic field on the accuracy of the error propagation. Irrespective of the accuracy of the underlying track parameter propagation, the method of parallel integration of the derivatives is demonstrated to be significantly faster than even the simplest numerical scheme. The error propagation presented in this paper is part of the simultaneous track and error propagation (STEP) algorithm of the common ATLAS tracking software

Track parameter propagation through the application of a new adaptive Runge-Kutta-Nystrom method in the ATLAS experiment

In this paper we study several fixed step and adaptive Runge-Kutta methods suitable for transporting track parameters through an inhomogeneous magnetic field. Moreover, we present a new adaptive Runge-Kutta-Nystrom method which estimates the local error of the extrapolation without introducing extra stages to the original Runge-Kutta-Nystrom method. Furthermore, these methods are compared for propagation accuracy and computing cost efficiency in the simultaneous track and error propagation (STEP) algorithm of the common ATLAS tracking software. The tests show the new adaptive Runge-Kutta-Nystrom method to be the most computing cost efficient

Emeralds from the Delbegetey deposit (Kazakhstan): mineralogical characteristics and fluid-inclusion study

The aim of this study is to provide the first detailed mineralogical and fluid-inc1usion description of emeralds from the Delbegetey deposit (Kazakhstan). The characteristic features of Delbegetey emeralds are established: they have dissolution figures on crystal faces, bluish colour and distinct colour zoning; the refractive indices are ro = 1.566-1.570, E = 1.558-1.562, and the specific gravity is 2.65±0.005, relatively low for natural emeralds; they have very small concentrations of the impurities (Fe, Mg, Na and others) typical of other emeralds, and contain Cr and V; there is a significant preponderance of vapour in fluid inc1usions of all types and there is liquid-to-vapour homogenization of primary fluid inc1usions (at 395-420°C). The lattice oxygen isotope composition data obtained (0180 SMOW value of 11.3%0) situate the deposit within the range characteristic of other granite-related emerald deposits. Emerald crystallization took place in low-density (0.40-0.55 g/cm3 ) aqueous fluid, with the following chemical composition (mol.%): 75.6-97.4 HzO, 0.0-18.4 caz, 0.0-0.9 C~, and 4.06-9.65 wt.% NaCI equiv. salinity. According to the calculated isochores, the pressure offormation ofthe Delbegetey emeralds can be estimated at 570-1240 bar

Variative discrete geometrical modeling of one-dimensional contours with the given differential-geometric characteristics

RU: Рассматривается задача формирования пространственных одномерных обводов с закономерным изменением кривизны и кручения. Методика основана на формировании кривой по отдельным монотонным участкам, с последующей их стыковкой. UA: Розглядається задача формування просторових одновимірних обводів с закономірною зміною кривини та скруту. Методика заснована на формуванні кривої по окремим монотонним ділянкам наступною їх стиковкою. EN: The task of forming of spatial one-dimensional contours with regular change of curvature and torsion is considered. The method is based on the formation of a curve on a separate monotonous sections and their subsequent docking