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Quantum Mechanics and Its Applications
Published in Sergey Edward Lyshevski, Nano- and Micro-Electromechanical Systems, 2018
Following this idea, instead of the many-electron wave functions, the charge density for N-electron systems can be used. Only knowledge of the charge density is needed to perform analysis of molecular dynamics. The charge density is the function that describes the number of electrons per unit volume (function of three spatial variables x, y, and z in the Cartesian coordinate system). Quantum mechanics and quantum modeling must be applied to understand and analyze nanostructures and nanodevices because they operate under the quantum effects.
CAD System-Boundary Integral Equation Method for 3D Electric Field Analysis of Voltage Transformers
Published in Xose M. López-Fernández, H. Bülent Ertan, Janusz Turowski, Transformers, 2017
Ivan Yatchev, Radoslav Miltchev
Figure 16.7 shows the color map of the obtained charge density on the boundary surfaces for the basic VT. The approach with mesh refinement in the azimuthal direction and approximation of the surface charge density has been employed. On electrode boundaries, that is, on the windings and the core, the charge density is proportional to the field intensity. The most electrically loaded area is on the end part of the high-voltage winding on its lower part (i.e., close to the yoke). It is practical to present the results for the charge density divided by ε0, thus having the dimension of the electric field intensity.
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Published in Splinter Robert, Illustrated Encyclopedia of Applied and Engineering Physics, 2017
[general] Charge density on the surface of a conductor, evenly spread, defined by the total charge Q on the object, divided by the surface area A: σelec = Q/A. For a nonconductive medium the local charge density will be location specific since there is no free migration of charge. The charge surface density on a curved surface for a conductor will be a function of the radius of curvature, with greater charge density with smaller radius of curvature: σelec,r/σelec,R = R/r, where R denotes the large radius of curvature (such as defining the outline for the body of a rounded cone) and r the radius of curvature of the pointy tip (see Figure S.127).
First-principles calculations to investigate thermodynamic and mechanical behaviors of molybdenum-lanthanum alloy
Published in Journal of Nuclear Science and Technology, 2023
Lu Wang, Kun Jie Yang, Chenguang Liu, Yue-Lin Liu
Figure 3 plots the total density of states (TDOS) of La at SS, TIS and OIS, respectively. As can be seen, the TDOS cannot reflect the differences for La at three positions. To accurately describe the interaction of La with nearest neighbor (nn) Mo atoms, we need to give the partial density of states (PDOS) of 1nn Mo with La at different sites, as shown in Figure 4. It is clear to see that a relatively wide and high peak appears in the low-energy state (from −5.0 to −3.5 eV) when La is located at TIS, while there are no higher peaks when La stays at both OIS and SS. Apparently, there is a strong interaction between TIS-La and 1nn Mo atoms. Valence charge density plays a key role in the analysis of interatomic bonding, as charge accumulation/depletion is a direct indicator of the strengthening/weakening of atomic bond. To further gain the physical insights on the interaction between La and its nn Mo atoms, we show valence charge density distribution for La at three different sites, as shown in Figure 5. It is clearly seen that the TIS-La interacts strongly with its 1nn Mo atoms since the valence charge density between La and Mo atoms is much higher those of other two cases, suggesting that the TIS-La can form the strong metallic bonds with its 1nn Mo atoms. This corresponds to the higher peak of DOS for the interaction of TIS-La with 1nn Mo atoms mentioned above.
An ab-initio investigation of the electronic structure, chemical bonding and optical properties of Ba2HgS5 semiconductor
Published in Molecular Physics, 2020
Sikander Azam, Saleem Ayaz Khan, R. Khenata, S. H. Naqib, A. Abdiche, Ş. Uğur, A. Bouhemadou, Xiaotian Wang
To the best of our knowledge, no detailed investigation, using ab-initio approach, on the optical properties and chemical bonding of the Ba2HgS5 compound have been reported in the literature. Although the electronic band structure and density of states have been discussed theoretically using the VASP code, it would be worthwhile to perform calculations that highlight the importance of using the full potential calculations; therefore, all electrons’ full potential linear augmented plane wave scheme was used for the calculations of the electronic and optical properties of the Ba2HgS5 compound. It has been found here that the calculated band gap value shows better agreement with the experimental data as compared to that calculated by using the VASP code [42]. The energy dependent optical parameters provide us with information complementary to that obtained from the electronic band structure calculations. Study of optical constants is very important to explore the potential of the system of interest in possible optoelectronic device applications. The bonding properties are intimately linked with the charge density distribution. Bonding properties determine the structural stability, features of phonon spectrum and mechanical behavior under applied stress. All these are useful for potential applications of the system under study.
Physical properties of molybdenum monoboride: Ab-initio study
Published in Philosophical Magazine, 2018
Priyanka Rajpoot, Anugya Rastogi, U. P. Verma
Electron charge density identifies nature of bonding among different atoms. In order to understand charge transfer and nature of the chemical bond in MoB, the calculated 2-D charge density over (1 1 0) plane is shown in Figure 5(a). The calculated contour plot shows that the charge density lines around atom B are spherical on the plane which shows the sign of covalent bond with it. The electro-negativity values for Mo and B are 2.16 and 2.04, respectively. Small negativity difference results in charge sharing and is responsible for covalent bond nature. Figure 5(b) shows the nature of chemical bonding between atoms B and Mo. The atomic distances (bond length) between two nearest atoms are listed in Table 2. The calculated bond lengths are in excellent agreement with the experimental as well as the earlier reported theoretical data.