STUDY OF STRUCTURAL STABILITY OF WIGNER ELECTRON CRYSTAL

2000 ◽  
Vol 14 (17) ◽  
pp. 1767-1779 ◽  
Author(s):  
R. RAJESWARA PALANICHAMY ◽  
K. IYAKUTTI
Keyword(s):  
Ground State ◽  
Energy Surface ◽  
Three Dimensional ◽  
Present Calculation ◽  
Wannier Functions ◽  
Constant Energy ◽  
Bcc Lattice ◽  
The Stability ◽  
Ground State Energies ◽  
Electron Crystal

The ground state energies of the non-magnetic Wigner electron crystals corresponding to sc, bcc, fcc, diamond and perovskite structures are estimated and it is found that the bcc lattice still remains to be the stable known arrangement for three-dimensional Wigner electron crystal. Perovskite structure is not the stablest as claimed in a previous work, it is preferred only after fcc and sc. The stability is analysed taking different structures and assuming the possibility of the Wigner electrons having cubic or spherical constant energy surface, the region of occupation in momentum space, for a whole range of rs values (rs=20 to 200). The structure dependent Wannier functions, which give a proper localized representation for the Wigner electrons in the crystals are constructed and employed in the present calculation.

INVESTIGATION OF NON-MAGNETIC AND FERROMAGNETIC PHASES OF 3D ELECTRON CRYSTAL WITH NaCl AND CsCl STRUCTURES

2008 ◽  
Vol 22 (21) ◽  
pp. 3627-3640
Author(s):  
R. RAJESWARA PALANICHAMY ◽  
M. ANANDAJOTHI ◽  
A. JAWAHAR ◽  
K. IYAKUTTI
Keyword(s):  
Ground State ◽  
State Energy ◽  
Correlation Energy ◽  
Magnetic Phase ◽  
Ferromagnetic Phase ◽  
Density Region ◽  
Wannier Functions ◽  
Ground State Energies ◽  
Electron Crystal

The non-magnetic and ferromagnetic phases of 3D Wigner electron crystal are investigated using a localized representation of the electrons with NaCl and CsCl structures. The ground state energies of ferromagnetic and non-magnetic phases of Wigner electron crystal are computed in the range 10 ≤ rs ≥ 130. The role of correlation energy is suitably taken into account. The low density region favorable for the ferromagnetic phase is found to be 4.8 × 1020 electrons/cm3 and for the non-magnetic phase, it is 2.03 × 1020 electrons/cm3. It is found that the ground state energy of ferromagnetic phase is less than that of the non-magnetic phase of the Wigner electron crystal. The structure-dependent Wannier functions, which give proper localized representation for Wigner electrons, are employed in the calculation.

EFFECT OF POSITIVE BACKGROUND ON THE FERROMAGNETIC PHASE OF 3D WIGNER ELECTRON CRYSTAL

2004 ◽  
Vol 18 (26) ◽  
pp. 3399-3408 ◽  
Author(s):  
R. RAJESWARA PALANICHAMY ◽  
K. IYAKUTTI
Keyword(s):  
Correlation Energy ◽  
Electron System ◽  
Ferromagnetic Phase ◽  
Low Density ◽  
Density Region ◽  
Wannier Functions ◽  
Fcc Lattice ◽  
Low Density Limit ◽  
The Stability ◽  
Ground State Energies

In the ferromagnetic phase of the 3D electron system, it is assumed that the spins of all the electrons are arranged in a parallel manner. The ferromagnetically ordered electrons are represented by the structure dependent Wannier functions. The ground state energies of the ferromagnetically ordered electron crystals corresponding to sc, bcc, fcc, diamond and perovskite structures are computed with Gaussian type and Yukawa type positive backgrounds. The stability of these structures is analyzed. In each case, the possibility of the Wigner electrons having cubic or spherical constant energy surface (the region of integration in momentum space) is considered for the range of rs values corresponding to low densities. The effect of correlation energy is suitably taken into account. The range of low density region favorable for Wigner crystallization is found to be at 6.0×1019/ cm 3. It is found that the ferromagnetically ordered electrons crystallize into fcc lattice in the low density limit with Yukawa type positive background.

DEVELOPMENT OF A THREE-DIMENSIONAL AB INITIO POTENTIAL ENERGY SURFACE FOR THE He–Cl2(X) SYSTEM AND ITS APPLICATION TO SOLVATION STRUCTURES IN THE HenCl2 CLUSTERS

2005 ◽  
Vol 04 (01) ◽  
pp. 197-207 ◽  
Author(s):  
TOSHIYUKI TAKAYANAGI ◽  
MOTOYUKI SHIGA ◽  
TETSUYA TAKETSUGU
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Ab Initio ◽  
Ground State ◽  
Energy Surface ◽  
Three Dimensional ◽  
Electronic Ground State ◽  
Basis Set ◽  
Electronically Excited ◽  
Electronic Ground

High-quality ab initio electronic structure calculations for the van der Waals interaction of He with Cl 2 in the electronic ground state have been carried out to develop a new three-dimensional potential energy surface for this system. The calculations were performed at the single and double excitation coupled-cluster level of theory with non-iterative perturbational treatment of triple excitations [CCSD(T)] with a very large basis set including an additional set of bond functions. The analytical potential surface developed were then used in the path-integral molecular dynamics calculations for the He n Cl 2 cluster, where quantum solvation structures of helium atoms in clusters were investigated. It has been found that the helium solvation structures are quite different between the electronic ground state and the electronically excited B 3Π state.

INVESTIGATION OF THE FERROMAGNETIC PHASE OF WIGNER ELECTRON CRYSTAL

2002 ◽  
Vol 16 (09) ◽  
pp. 1353-1361 ◽  
Author(s):  
R. RAJESWARA PALANICHAMY ◽  
K. IYAKUTTI
Keyword(s):  
Correlation Energy ◽  
Ferromagnetic Phase ◽  
Low Density ◽  
Density Region ◽  
Wannier Functions ◽  
Fcc Lattice ◽  
Low Density Limit ◽  
The Stability ◽  
Ground State Energies

The ground state energies of the ferromagnetically ordered electron crystals corresponding to sc, bcc, fcc, diamond and perovskite structures are computed. The stability of these structures is analyzed. In each case, the possibility of the Wigner electrons having cubic or spherical constant energy surface (the region of integration in momentum space) is considered for the range of r s values corresponding to low densities. The role of correlation energy is suitably taken into account. The range of low density region favourable for Wigner crystallization is found to be above r s = 30. It is found that, the ferromagnetically ordered electrons crystallize into fcc lattice in the low density limit. The structure dependent Wannier functions, which give proper localized representation for the Wigner electrons in the crystal, are employed in the calculation.

VARIATIONAL COMPUTATIONS FOR EXCITONS IN QUANTUM DOTS: A QUANTUM MONTE CARLO STUDY

2011 ◽  
Vol 25 (01) ◽  
pp. 119-130
Author(s):  
A. YILDIZ ◽  
S. ŞAKİROĞLU ◽  
Ü. DOĞAN ◽  
K. AKGÜNGÖR ◽  
H. EPİK ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Monte Carlo ◽  
Ground State ◽  
Quantum Monte Carlo ◽  
Three Dimensional ◽  
Monte Carlo Study ◽  
Wave Functions ◽  
Monte Carlo Techniques ◽  
Oscillator Basis ◽  
Ground State Energies

A study of variational wave functions for calculation of the ground-state energies of excitons confined in a two-dimensional (2D) disc-like and three-dimensional (3D) spherical parabolic GaAs quantum dots (QDs) is presented. We have used four variational trial wave functions constructed as the harmonic-oscillator basis multiplied by different correlation functions. The proposed correlation function formed by including linear expansion in terms of Hylleraas-like coordinates to the Jastrow factor is able to capture nearly exactly the ground-state energies of 3D excitons, and it properly account for the results of 2D excitons. Quantum Monte Carlo techniques combined with the proposed wave function are a powerful tool for studying excitons in parabolic QDs.

FORMATION AND STABILITY OF A STRONG-COUPLING LARGE BIPOLARON IN THE LIGHTLY DOPED CUPRATES

2005 ◽  
Vol 19 (06) ◽  
pp. 1061-1064
Author(s):  
E. DUSHANOV ◽  
S. DZHUMANOV
Keyword(s):  
Ground State ◽  
Stability Region ◽  
Continuum Model ◽  
Adiabatic Approximation ◽  
Three Dimensional ◽  
Dielectric Constants ◽  
Coulomb Correlation ◽  
Ground State Energies ◽  
Broad Region ◽  
The Continuum

The ground-state energies of large polaron Ep and bipolaron EB in three-dimensional lightly doped cuprates are calculated variationally taking into account the short- and long-range electron-phonon interactions and Coulomb correlation in the continuum model and adiabatic approximation. The binding energy of a large bipolaron and its stability region are determined as a function of the ratio of dielectric constants η = ε∞/ε0. It is found that the large bipolaron is stable in a broad region of η.

A Liquid Metal Flow Between Two Coaxial Cylinders System

2019 ◽  
Vol 11 (1) ◽  
pp. 79-86
Author(s):  
Abdelkrim Merah ◽  
Ridha Kelaiaia ◽  
Faiza Mokhtari
Keyword(s):  
Couette Flow ◽  
Metal Flow ◽  
Three Dimensional ◽  
Liquid Sodium ◽  
Taylor Vortex ◽  
Turbulent Regime ◽  
Coaxial Cylinders ◽  
Concentric Cylinders ◽  
Ideal Tool ◽  
The Stability

Abstract The Taylor-Couette flow between two rotating coaxial cylinders remains an ideal tool for understanding the mechanism of the transition from laminar to turbulent regime in rotating flow for the scientific community. We present for different Taylor numbers a set of three-dimensional numerical investigations of the stability and transition from Couette flow to Taylor vortex regime of a viscous incompressible fluid (liquid sodium) between two concentric cylinders with the inner one rotating and the outer one at rest. We seek the onset of the first instability and we compare the obtained results for different velocity rates. We calculate the corresponding Taylor number in order to show its effect on flow patterns and pressure field.

Handheld Laser Scanner Research

2019 ◽  
Vol 952 (10) ◽  
pp. 47-54
Author(s):  
A.V. Komissarov ◽  
A.V. Remizov ◽  
M.M. Shlyakhova ◽  
K.K. Yambaev
Keyword(s):  
Point Cloud ◽  
Three Dimensional ◽  
Laser Scanner ◽  
Test Site ◽  
Optical Systems ◽  
Advantages And Disadvantages ◽  
Site Survey ◽  
Laser Scanners ◽  
Three Dimensional Models ◽  
The Stability

The authors consider hand-held laser scanners, as a new photogrammetric tool for obtaining three-dimensional models of objects. The principle of their work and the newest optical systems based on various sensors measuring the depth of space are described in detail. The method of simultaneous navigation and mapping (SLAM) used for combining single scans into point cloud is outlined. The formulated tasks and methods for performing studies of the DotProduct (USA) hand-held laser scanner DPI?8X based on a test site survey are presented. The accuracy requirements for determining the coordinates of polygon points are given. The essence of the performed experimental research of the DPI?8X scanner is described, including scanning of a test object at various scanner distances, shooting a test polygon from various scanner positions and building point cloud, repeatedly shooting the same area of the polygon to check the stability of the scanner. The data on the assessment of accuracy and analysis of research results are given. Fields of applying hand-held laser scanners, their advantages and disadvantages are identified.

Energies and Electric Dipole Moments of the Bound Vibrational States of HN2+ and DN2+

2008 ◽  
Vol 73 (6-7) ◽  
pp. 873-897 ◽  
Author(s):  
Vladimír Špirko ◽  
Ota Bludský ◽  
Wolfgang P. Kraemer
Keyword(s):  
Dipole Moment ◽  
Nearest Neighbor ◽  
Energy Surface ◽  
Dipole Moments ◽  
Three Dimensional ◽  
Vibrational States ◽  
Spacing Distribution ◽  
Triatomic Molecules ◽  
Vibrational Levels ◽  
Different Levels

The adiabatic three-dimensional potential energy surface and the corresponding dipole moment surface describing the ground electronic state of HN2+ (Χ1Σ+) are calculated at different levels of ab initio theory. The calculations cover the entire bound part of the potential up to its lowest dissociation channel including the isomerization barrier. Energies of all bound vibrational and low-lying ro-vibrational levels are determined in a fully variational procedure using the Suttcliffe-Tennyson Hamiltonian for triatomic molecules. They are in close agreement with the available experimental numbers. From the dipole moment function effective dipoles and transition moments are obtained for all the calculated vibrational and ro-vibrational states. Statistical tools such as the density of states or the nearest-neighbor level spacing distribution (NNSD) are applied to describe and analyse general patterns and characteristics of the energy and dipole results calculated for the massively large number of states of the strongly bound HN2+ ion and its deuterated isotopomer.

Ultraviolet photodissociation dynamics of PCl3 at 235 nm: three-dimensional ion imaging and theoretical analysis

2021 ◽  
Author(s):  
Alexei Chichinin ◽  
Christof Maul ◽  
Karl-Heinz Gericke
Keyword(s):  
Theoretical Analysis ◽  
Ground State ◽  
Multiphoton Ionization ◽  
Three Dimensional ◽  
Ion Imaging ◽  
Ultraviolet Photodissociation

The photodissociation dynamics of PCl3 at 235 nm has been studied by monitoring ground state Cl(2P3/2) and spin-orbitally excited Cl(2P1/2) atoms by resonance enhanced multiphoton ionization(REMPI). Also, the PCl+n (n=0,1,2)...

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