Papers by Keyword: Electron Density

Abstract: We have calculated the energies of excited states for the He, Li, and Be atoms by the time dependent self-consistent Kohn Sham equation using the Coulomb Wave Function Discrete Variable Representation CWDVR) approach. The CWDVR approach was used the uniform and optimal spatial grid discretization to the solution of the Kohn-Sham equation for the excited states of atoms. Our results suggest that the CWDVR approach is an efficient and precise solutions of excited-state energies of atoms. We have shown that the calculated electronic energies of excited states for the He, Li, and Be atoms agree with the other researcher values.

Abstract: We developed the photon counting CT system by using a conventional laboratory X-ray source and a CdTe line sensor. Attenuation coefficients were obtained from the measured CT image data. Our suggested method for deriving the electron density and effective atomic number from the measured attenuation coefficients was tested experimentally. The accuracy of the electron densities and effective atomic numbers are about <5 % (the averages of absolute values are 2.6 % and 3.1 %, respectively) for material of 6< Z and Zeff <13. Our suggested simple method, in which we do not need the exact source X-ray spectrum and detector response function, achieves comparable accuracy to the previous reports.

Abstract: We explore the structural and electronic properties of a single layer arsenene using the state of art, first principle approach from density functional theory (DFT). All the calculation was conducted using an open source DFT code, adopted the planewaves (PWs) method by Quantum Espresso (QE). The calculation utilized an exchange correlation potential of electron parametrized by Perdew-Burke-Ernzerhof (PBE) under generalized gradient approximation (GGA) functional scheme. Meanwhile, the pseudopotential assigned for the core electron is the projector typed augmented-wave with the core potential correction, generated using "atomic" code. All those parameters resulted an optimized structure of the honeycomb arsenene with lattice constant of 4.4971 Ǻ. The arsenene layer occupy a bond length value of 2.5964 Ǻ as measured between its neighbouring bonded atoms. From an optimized structure, we explore its electronic bandstructure plotted from 3 highly symmetries point for 2-dimensional (2D) material known as ‘’, ‘’ and ‘’ with 3 electron pathways. The total number of bands considered in bandstruture plotting is 10, where 5 bands will consider as valance bands while another 5 is conduction bands. The bandstructure shows that a single layer flat arsenene exhibits the characteristics of a conductor due to the overlapping of band near to Fermi level. Dirac cone were also noticed near to the Fermi energy level of the bandstructure. Lastly, we study the total electron density for the whole structure to reveal its bonding characteristics. The contour plot of electron densities between two bounded atoms displayed a pure covalent bond characteristic. The findings of this work is expected to contribute to the key of the electronic devices development, optoelectronics, and sensor devices based on 2D material technology.Keywords: flat layer arsenene, density of state, electron density, electronic band structure

Abstract: The topology of electron density is a sketch that gives a clear picture about electronic distribution and details information of natural molecular bonding. In quantum mechanics or particularly in quantum chemistry, the electron density is a measure of the probability of an electron occupying at any infinitesimal element of space surrounding at any given point.Studies about the topology of electron density in Cd_0.5Zn_0.5S at plane (101) were conducted by the application of density functional theory (DFT) within linear augmented plane wave (LAPW) by using the WIEN2k software. In this calculation, generalized gradient approximation (GGA) methods were used to calculate the exchange-correlation potential of the electrons. Based on this calculation, the topology of electron density were presented in a contour plot (2D) and also inarelief map plot (3D) in order to see the way electron density, ρ of Cd_0.5Zn_0.5S defines the gradient field and hence the bonding type. From these plots, we identified the bond paths that coincide with the contours of electron to suggest that Cd_0.5Zn_0.5S exhibited characteristics of covalent and a slightly ionic bond character.

Abstract: The phenomenological approach based on analysis the crystal-chemical parameters and their change depending on concentration of the alloying element for definition of concentration intervals of existence of stable phases with ordered structures in the ternary Titanium Nickelide based alloys is described. It was shown that a comparison of the data of change patterns in crystal-chemical parameters phenomenologically predicted and obtained from experimental data, allows to predict some of the conditions of stabilization in the examined phase, the solubility limits of alloying elements and, consequently, its homogeneity region, as well as formation conditions of multiphase systems. The analysis carried out allows us to make a conclusion regarding the issue that is often discussed in the analysis of phase diagrams of binary and multicomponent systems - what is the ratio of the size and electronic contributions to the stability of the phases. It was shown that the contribution of the size factor to the stabilization of B2 and B19(or В19′) phases is predominant and the role of this factor grows with the increase in the amount of the alloying element.

Abstract: In this paper, we use PLASIMO to investigate the effect of discharge current on hydrogen plasma in the cascaded arc, the effects of discharge current on plasma properties were investigated. temperature, conductivity, and the distribution of electron density along the symmetry axis of hydrogen plasma is analyzed in the simulation area. The simulation results show that plasma temperature is 0.9503×104, 1.09862×104, 1.26675×104, 1.65102×104 K in the symmetry axis when the discharge current is 35, 50, 75 and 100A, meanwhile, electric conductivity is 1738.03, 2272.72, 2819.86, 3820.73 s/m.

Abstract: Numerical calculations with time dependant one-dimensional fluid model are performed at various conditions in argon atmospheric pressure to calculate electrical characteristics and plasma parameters including charged and metastable molecules densities. The simulation results show after steady discharge are formed, the voltage of discharge gap nearly remain constant and the phase is 0.36π advance of the applied voltage; The current density are in the same period as the applied voltage, the phase is 0.58π ahead of the applied voltage; The steady state Ar are in high number density in the whole discharge gap; The Ar* number density appear peak at the middle of the discharge gap; The Ar⁺ number density appear peak in the negative bright area.

Abstract: A number of X···F (X=C, N, O and S) noncovalent weak intermolecular interaction systems of CH₃-F···XO₂ (X=C, N, O and S) has been investigated at B3LYP/6-311++G(d, p) computational level. A topological analysis of the electron density for the X···F (X=C, N, O and S) noncovalent weak bonds was performed using Baders theory of atom-in-molecules (AIM). The interaction content of the F···X in H₃CF···CO₂ complex would mainly represent more π property than others. The interaction energies data without (ΔE) and with (ΔE_cp) BSSE correction showed that the stability of the four complexes of the H₃CF···DB₂ system increases in the order of H₃CF···O₃ < H₃CF···NO₂ < H₃CF···CO₂ < H₃CF···SO₂.

Abstract: Argon plasma jet in a single-electrode configuration was generated at low temperature and atmospheric pressure by 50 kHz radiofrequency power supply. Optical Emission Spectroscopy (OES) was used to investigate the local emissivity of argon plasma in the range between 200 and 1,100 nm. The spatial distribution of reactive species was measured at different distances of the plasma expansion from the nozzle exit such as 0.0, 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 cm. These measurements were obtained to analyze the plasma parameters such as electron temperature and electron density. The effect of distances of the plasma expansion from the nozzle exit on the plasma parameters was studied. The main intensive argon lines were found in the region between 690 and 970 nm. The electron temperature was found in the range of 0.5-1.1 eV. The electron density was found in the range of 4.0x10¹²-1.2x10¹³ cm^-3. The plasma parameters strongly depended on the distances of the plasma expansion from the nozzle exit.

Abstract: We report on the characteristics of argon inductively coupled plasma (ICP) for the ITER neutral beam injection system. In argon ICP, it was found by using Langmuir probe that the radial distribution of electronic density (N_e) was uniform while the radial distributions of both electron temperature (kT_e ) and electric potential (V_P) were non-uniform. The former depend on two factors: the variation of N_e was small, and the value of N_e was very large. The latter is owing to the generation and disappearance of the negative ions in the ICP, where the additional dynamic processes produce the instability. In addition, both kT_e and V_P profiles were very similar at the cylinder height H=14 cm, which proves the plasma sheath theory to some extent. Finally, both kT_e and V_P began flatter with the reduction of the cylinder height, which is owing to the decrease of the negative ions in the ICP.