Impact of Co Atoms on the Electronic Structure of Bi2Te3 and MnBi2Te4 Topological Insulators

Journal of Experimental and Theoretical Physics - This work is devoted to an experimental investigation of the electronic structure of the surface of topological insulators of various stoichiometry...     

Qualitative and Numerical Analysis of a Cosmological Model Based on an Asymmetric Scalar Doublet with Minimal Connections. III. Multiply-Connected Factor and Character of the Singular Points

Russian Physics Journal - On the basis of a qualitative and numerical analysis of a cosmological model based on an asymmetric scalar doublet of nonlinear, minimally interacting scalar fields, both...     

Qualitative and Numerical Analysis of a Cosmological Model Based on an Asymmetric Scalar Doublet with Minimal Couplings. II. Numerical Modeling of Phase Trajectories

Russian Physics Journal - With the help of our own software package DifEqTools, numerical modeling of the cosmological evolution of a system consisting of an asymmetric scalar doublet of nonlinear,...     

An anti-diffusive numerical scheme for the simulation of interfaces between compressible fluids by means of a five-equation model

We propose a discretization method of a five-equation model with isobaric closure for the simulation of interfaces between compressible fluids. This numerical solver is a Lagrange–Remap scheme that aims at controlling the numerical diffusion of the interface between both fluids. This method does not involve any interface reconstruction procedure. The solver is equipped with built-in stability and consistency properties and is conservative with respect to mass, momentum, total energy and partial masses. This numerical scheme works with a very broad range of equations of state, including tabulated laws. Properties that ensure a good treatment of the Riemann invariants across the interface are proven. As a consequence, the numerical method does not create spurious pressure oscillations at the interface. We show one-dimensional and two-dimensional classic numerical tests. The results are compared with the approximate solutions obtained with the classic upwind Lagrange–Remap approach, and with experimental and previously published results of a reference test case.     

Reactivity of chemisorbed hydrogen species on Pt towards acetylene

In the presence of both molecular and atomic hydrogen on catalyst surface, C₂H₂ is hydrogenated directly to C₂H₆. In the presence of atomic hydrogen only, the reaction can also have another route to form C₂H₄.

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, C₂H₂ C₂H₆, , C₂H₄.

     

Analysis of coefficient identification problems associated to the inverse Euler-Bernoulli beam theory

A rigorous investigation of the identification of a heterogeneousflexural rigidity coefficient in the Euler-Bernoulli steady-statebeam theory in the presence of a prescribed load is presented.Mathematically, this study is an extension to higher-order differentialequations of the coefficient identification problem analysedby Marcellini (1982) for the one-dimensional Poisson equation.In addition, various types of boundary conditions are discussed.Conditions for the well-posedness of these inverse problemsare established and, furthermore, numerical results obtainedusing a regularization algorithm are presented.     

A critical investigation of the effects of the radio frequency potential on the trapping of externally injected ions in ion trap mass spectrometry

The sensitivity of all ion trap mass spectrometry (ITMS) methods is dependent on the trapping efficiency of the instrument. For ITMS instruments utilizing external ion sources, such as laser desorption, trapping efficiency is known to depend on the phase and amplitude of the radio frequency (RF) potential applied to the ring electrode at the time of ion introduction. It is remarkable that, in a considerable body of literature, no consensus exists regarding the effects of these parameters on the efficacy of trapping externally generated ions. In this paper, a summary of the literature is presented in order to highlight significant discrepancies. New laser desorption ion trap mass spectrometry (LD-ITMS) data are also presented, from which conclusions are drawn in our effort to clarify some of the confusion. Copyright 1999 John Wiley & Sons, Ltd.     

Study of the covalent and triplet ionic-pairing states of the fluorine molecule with the MRDCI method

The results of nonempirical calculations of the electronic structure, spectroscopic constants, and potential-energy curves for the covalent and triplet ionic-pairing states of the F₂ molecule are presented. It is shown that the covalent 1³Π_u state is weakly bound, with the depth of the potential well of this state being of about 0.05–0.2 eV. The effect of the spin-orbital interaction on the ionic-pairing states, which can result in the perturbation of the Ω=0⁺ and Ω=1 components of the ³Σ _u ^? and ³Π_u states, is analyzed. It is demonstrated that the lasing observed at λ ≈ 157 nm is caused by the transitions between the ionic-pairing state 2³Π_g and the weakly bound covalent state 1³Π_u.     

Phase formation in the BaB2O4-BaF2 system

It is shown that the BaB₂O₄-BaF₂ system is quasi-binary with the following eutectics coordinates: 760°C, 59 mol % BaF₂, 41 mol % BaB₂O₄. Due to the intense pyrohydrolysis during the growth of ??-BaB₂O₄ crystals from the 55.6 mol % BaB₂O₄-44.4 mol % BaF₂ composition, the Ba₅B₄O₁₁ compound is formed in the system. This process leads to the cocrystallization of the ??-BaB₂O₄ and Ba₅B₄O₁₁ phases and impedes the formation of high-quality crystals.