The Electron Density and the Lattice Energy of Crystals

1997 ◽  
Author(s):  
Philip Coppens
Keyword(s):  
Kinetic Energy ◽  
Total Energy ◽  
Mechanical System ◽  
Charge Distribution ◽  
Electron Density ◽  
Electron Correlation ◽  
Lattice Energy ◽  
Quantum Mechanical ◽  
Electron Repulsion ◽  
Electron Attraction

The total energy of a quantum-mechanical system can be written as the sum of its kinetic energy T, Coulombic energy ECoui and exchange and electron correlation contributions Ex and Ecorr, respectively: . . . E=T+Ecoui+Ex+Ecorr (9.1) . . . The only term in this expression that can be derived directly from the charge distribution is the Coulombic energy. It consists of nucleus–nucleus repulsion, nucleus–electron attraction, and electron–electron repulsion terms.

scholarly journals Quantum mechanical modelling of phosphorus qubits in silicene under constrained magnetization

RSC Advances ◽  
2021 ◽  
Vol 11 (54) ◽  
pp. 33890-33894
Author(s):  
Anton A. Gnidenko ◽  
Andrey N. Chibisov ◽  
Mary A. Chibisova ◽  
Anastasiia V. Prokhorenko
Keyword(s):  
Total Energy ◽  
Charge Distribution ◽  
Magnetic Moment ◽  
Dft Calculation ◽  
Local Magnetic Moment ◽  
Quantum Mechanical ◽  
Distribution Change ◽  
Mechanical Modelling ◽  
Dependent Behaviour

The dependent behaviour of a pair of phosphorus atoms in silicene was shown by a DFT calculation with constrained magnetization. The total energy and charge distribution change with the rotation of the local magnetic moment of the P atoms.

scholarly journals Hydrodynamic constraints on the energy efficiency of droplet electricity generators

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Antoine Riaud ◽  
Cui Wang ◽  
Jia Zhou ◽  
Wanghuai Xu ◽  
Zuankai Wang
Keyword(s):  
Energy Efficiency ◽  
Kinetic Energy ◽  
Total Energy ◽  
Viscous Dissipation ◽  
Shear Force ◽  
Mechanical Energy ◽  
Electric Energy ◽  
The Past ◽  
Viscous Shear ◽  
Impingement Velocity

AbstractElectric energy generation from falling droplets has seen a hundred-fold rise in efficiency over the past few years. However, even these newest devices can only extract a small portion of the droplet energy. In this paper, we theoretically investigate the contributions of hydrodynamic and electric losses in limiting the efficiency of droplet electricity generators (DEG). We restrict our analysis to cases where the droplet contacts the electrode at maximum spread, which was observed to maximize the DEG efficiency. Herein, the electro-mechanical energy conversion occurs during the recoil that immediately follows droplet impact. We then identify three limits on existing droplet electric generators: (i) the impingement velocity is limited in order to maintain the droplet integrity; (ii) much of droplet mechanical energy is squandered in overcoming viscous shear force with the substrate; (iii) insufficient electrical charge of the substrate. Of all these effects, we found that up to 83% of the total energy available was lost by viscous dissipation during spreading. Minimizing this loss by using cascaded DEG devices to reduce the droplet kinetic energy may increase future devices efficiency beyond 10%.

STRUCTURE, STABILITY, AND ELECTRONIC PROPERTIES OF LARGE FULLERENES

1993 ◽  
Vol 07 (26) ◽  
pp. 4305-4329 ◽  
Author(s):  
C.Z. WANG ◽  
B.L. ZHANG ◽  
K.M. HO ◽  
X.Q. WANG
Keyword(s):  
Total Energy ◽  
Electronic Properties ◽  
Ground State ◽  
Relative Stability ◽  
Chemical Reactivity ◽  
Structure Stability ◽  
Quantum Mechanical ◽  
Efficient Scheme ◽  
Ground State Structures ◽  
Fullerene Clusters

The recent development in understanding the structures, relative stability, and electronic properties of large fullerenes is reviewed. We describe an efficient scheme to generate the ground-state networks for fullerene clusters. Combining this scheme with quantum-mechanical total-energy calculations, the ground-state structures of fullerenes ranging from C 20 to C 100 have been studied. Fullerenes of sizes 60, 70, and 84 are found to be energetically more stable than their neighbors. In addition to the energies, the fragmentation stability and the chemical reactivity of the clusters are shown to be important in determining the abundance of fullerene isomers.

scholarly journals Topology of the Electron Density and of Its Laplacian from Periodic LCAO Calculations on f-Electron Materials: The Case of Cesium Uranyl Chloride

Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4227
Author(s):  
Alessandro Cossard ◽  
Silvia Casassa ◽  
Carlo Gatti ◽  
Jacques K. Desmarais ◽  
Alessandro Erba
Keyword(s):  
Electron Density ◽  
Chemical Bonding ◽  
Topological Analysis ◽  
Theoretical Description ◽  
Basis Functions ◽  
Quantum Mechanical ◽  
X Ray Diffraction ◽  
X Ray ◽  
Atomic Orbitals ◽  
Uranyl Chloride

The chemistry of f-electrons in lanthanide and actinide materials is yet to be fully rationalized. Quantum-mechanical simulations can provide useful complementary insight to that obtained from experiments. The quantum theory of atoms in molecules and crystals (QTAIMAC), through thorough topological analysis of the electron density (often complemented by that of its Laplacian) constitutes a general and robust theoretical framework to analyze chemical bonding features from a computed wave function. Here, we present the extension of the Topond module (previously limited to work in terms of s-, p- and d-type basis functions only) of the Crystal program to f- and g-type basis functions within the linear combination of atomic orbitals (LCAO) approach. This allows for an effective QTAIMAC analysis of chemical bonding of lanthanide and actinide materials. The new implemented algorithms are applied to the analysis of the spatial distribution of the electron density and its Laplacian of the cesium uranyl chloride, Cs2UO2Cl4, crystal. Discrepancies between the present theoretical description of chemical bonding and that obtained from a previously reconstructed electron density by experimental X-ray diffraction are illustrated and discussed.

Nonnuclear Maxima in the Charge Density

1993 ◽  
Vol 48 (1-2) ◽  
pp. 127-133 ◽  
Author(s):  
Kenneth E. Edgecombe ◽  
Vedene H. Smith, Jr. ◽  
Florian Müller-Plathe
Keyword(s):  
Charge Density ◽  
Electron Density ◽  
Electron Correlation ◽  
Basis Set ◽  
Valence Shell ◽  
Correlation Effects ◽  
Electron Correlation Effects

Abstract Basis-set and electron-correlation effects on the appearance and disappearance of nonnuclear maxima in the electron density are examined in Li2 , Na2 , Na4 and Na5 . It is shown that nonnuclear attractors can be removed in all cases except Li2 . The appearance of a pseudoatom in a lithium molecule correlates remarkably well with the size of the region, in an atomic calculation, of V2r(r) for the valence shell of the atom. This and the fact that the pseudoatom is also present in the promolecule indicate that the pseudoatoms are remnants of, or in fact are portions of, atoms that are not perturbed enough in the molecule to remove an essentially atomic characteristic.

DEVELOPMENT OF CONSTRUCTION OF THREE-INPUT GENERATING INSTALLATIONS ON BASED OF RENEWABLE ENERGY SOURCES

2018 ◽  
Author(s):  
Я.М. КАШИН ◽  
Л.Е. КОПЕЛЕВИЧ ◽  
А.В. САМОРОДОВ ◽  
Ч. ПЭН
Keyword(s):  
Renewable Energy ◽  
Kinetic Energy ◽  
Total Energy ◽  
Thermal Energy ◽  
Output Voltage ◽  
Renewable Energy Sources ◽  
Electrical Energy ◽  
Energy Sources ◽  
Voltage Regulator ◽  
The Sun

Описаны конструктивные особенности трехвходовой аксиальной генераторной установки (ТАГУ), преобразующей кинетическую энергию ветра и световую энергию солнца и суммирующей механическую, световую и тепловую энергию с одновременным преобразованием полученной суммарной энергии в электрическую. Показаны преимущества ТАГУ перед двухвходовыми генераторными установками. Дополнительное включение стабилизатора напряжения в схему ТАГУ позволило расширить область применения стабилизированной трехвходовой аксиальной генераторной установки за счет стабилизации ее выходного напряжения. The design features of the three-input axial generating installation (TAGI), which converts the kinetic energy of wind and light energy of the sun and sums the mechanical, light and thermal energy with the simultaneous conversion of the total energy into electrical energy, are described. The benefits of TAGI in front of the two-input generating installation shown. The additional introduction of a voltage regulator into the TAGI scheme allowed to expand the scope of the stabilized three-input axial generating installation by stabilizing its output voltage.

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