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  • PLASMA PHYSICS  (7)
  • Nuclear Reactions  (3)
  • Atomic, Molecular and Optical Physics  (2)
  • 1
    Electronic Resource
    Electronic Resource
    New method for the direct calculation of electron density in many-electron systems. I. Application to closed-shell atoms (1983)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 23 (1983), S. 1-26 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new density-functional equation is suggested for the direct calculation of electron density ρ(r) in many-electron systems. This employs a kinetic energy functional T2 + f(r)T0, where T2 is the original Weizsäcker correction, T0 is the Thomas-Fermi term, and f(r) is a correction factor that depends on both r and the number of electrons N. Using the Hartree-Fock relation between the kinetic and the exchange energy density, and a nonlocal approximation to the latter, the kinetic energy-density functional is written (in a.u.) \documentclass{article}\pagestyle{empty}\begin{document}$$ t[\rho] = {\raise0.7ex\hbox{$1$} \!\mathord{\left/ {\vphantom {1 4}}\right.\kern-\nulldelimiterspace}\!\lower0.7ex\hbox{$4$}}\nabla ^2 \rho + {\raise0.7ex\hbox{$1$} \!\mathord{\left/ {\vphantom {1 8}}\right.\kern-\nulldelimiterspace}\!\lower0.7ex\hbox{$8$}}(\nabla \rho \cdot \nabla \rho)/\rho + C_k f({\bf r})\rho ^{5/3}, $$\end{document} where \documentclass{article}\pagestyle{empty}\begin{document}$ C_k = {\raise0.7ex\hbox{$2$} \!\mathord{\left/ {\vphantom {2 {10}}}\right.\kern-\nulldelimiterspace}\!\lower0.7ex\hbox{${10}$}}(3\pi ^2)^{2/3} $\end{document}. Incorporating the above expression in the total energy density functional and minimizing the latter subject to N representability conditions for ρ(r) result in an Euler-Lagrange nonlinear second-order differential equation \documentclass{article}\pagestyle{empty}\begin{document}$$ \left[{ - {\raise0.7ex\hbox{$1$} \!\mathord{\left/ {\vphantom {1 2}}\right.\kern-\nulldelimiterspace}\!\lower0.7ex\hbox{$2$}}\nabla ^2 + v_{{\rm nuc}} ({\bf r}) + v_{{\rm cou}} ({\bf r}) + v_{XC} ({\bf r}) + {\raise0.7ex\hbox{$5$} \!\mathord{\left/ {\vphantom {5 3}}\right.\kern-\nulldelimiterspace}\!\lower0.7ex\hbox{$3$}}C_k g({\bf r})\rho ^{2/3}} \right]\phi ({\bf r}) = \mu \phi ({\bf r}) $$\end{document} where μ is the chemical potential, we have ρ(r) = |φ(r)|2, and g(r) is related to f(r). Numerical solutions of the above equation for Ne, Ar, Kr, and Xe, by modeling f(r) and g(r) as simple sums over Gaussians, show excellent agreement with the corresponding Hartree-Fock ground-state densities and energies, indicating that this is likely to be a promising method for calculating fairly accurate electron densities in atoms and molecules.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560230104
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Quantum fluid dynamics of many-electron systems in three-dimensional space (1982)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 22 (1982), S. 871-888 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In presence of external electric and magnetic fields, the Schrödinger equation for many-electron systems is transformed into a continuity equation and an Euler-type equation of motion in configuration space. Then, using the natural-orbital Hamiltonian, as defined by Adams, the two fluid-dynamical equations are derived in the three-dimensional space. This generates a “classical” view of such quantum systems, corresponding to an MCSCF wave function: The many-electron Schrödinger fluid consists of individual fluid components, each corresponding to a natural orbital and having its own charge density and current density. The local observables, viz., the net charge density and net current density, are obtained by merely summing over the natural orbitals, with the occupation numbers as weight factors; but, the net velocity field cannot be so obtained. Further, although each fluid component moves irrotationally in the absence of a magnetic field, the net velocity field is not irrotaional. The irrotational character of each velocity component is destroyed by rotation of the nuclear framework of the system while electron spin introduces an additional term, the spin magnetization moment, into each component current density. The physical significance of the fluid-dynamical equations as well as their advantages and disadvantages are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560220503
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  • 3
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    Evidence of quasifission in the ^{16} O +  ^{238} U reaction at sub-barrier energies (2011)
    American Physical Society (APS)
    Details
    Publication Date: 2011-02-10
    Description: Author(s): K. Banerjee, T. K. Ghosh, S. Bhattacharya, C. Bhattacharya, S. Kundu, T. K. Rana, G. Mukherjee, J. K. Meena, J. Sadhukhan, S. Pal, P. Bhattacharya, K. S. Golda, P. Sugathan, and R. P. Singh Mass distribution of fission fragments and neutron multiplicity in the ^{16} O+^{238} U reaction were measured at near- and below-barrier energies. A sudden change in the fragment mass width, observed in the present measurement, confirmed the transition to quasifission at below-barrier energies; the... [Phys. Rev. C 83, 024605] Published Wed Feb 09, 2011
    Keywords: Nuclear Reactions
    Print ISSN: 0556-2813
    Electronic ISSN: 1089-490X
    Topics: Physics
    Published by American Physical Society (APS)
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  • 4
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    Fragment emission mechanism in the ^{32} S+ ^{12} C reaction (2017)
    American Physical Society (APS)
    Details
    Publication Date: 2017-06-06
    Description: Author(s): Ratnesh Pandey, S. Kundu, C. Bhattacharya, K. Banerjee, T. K. Rana, S. Manna, G. Mukherjee, J. K. Meena, A. Chaudhuri, T. Roy, Pratap Roy, Md. A. Asgar, V. Srivastava, A. Dey, M. Sinha, T. K. Ghosh, S. Bhattacharya, S. K. Pandit, K. Mahata, P. Patle, S. Pal, A. Shrivastava, and V. Nanal The complex fragment emission from the decay of fully energy-relaxed composite, Ti * 44 formed via the S 32 + C 12 reaction at two excitation energies, have been studied. Inclusive energy distributions of the fragments ( 3 ≤ Z ≤ 8 ) emitted in the reaction S 32 + C 12 have been measured in the angular range ∼ 16 ∘ – 28 … [Phys. Rev. C 95, 064603] Published Mon Jun 05, 2017
    Keywords: Nuclear Reactions
    Print ISSN: 0556-2813
    Electronic ISSN: 1089-490X
    Topics: Physics
    Published by American Physical Society (APS)
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  • 5
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    Fission fragment mass distributions from $^{210}\mathrm{Po}$ and $^{213}\mathrm{At}$ (2017)
    American Physical Society (APS)
    Details
    Publication Date: 2017-12-19
    Description: Author(s): A. Sen, T. K. Ghosh, S. Bhattacharya, K. Banerjee, C. Bhattacharya, S. Kundu, G. Mukherjee, A. Asgar, A. Dey, A. Dhal, Md. Moin Shaikh, J. K. Meena, S. Manna, R. Pandey, T. K. Rana, Pratap Roy, T. Roy, V. Srivastava, and P. Bhattacharya Background : The influence of shell effect on the dynamics of the fusion fission process and its evolution with excitation energy in the preactinide Hg-Pb region in general is a matter of intense research in recent years. In particular, a strong ambiguity remains for the neutron shell closed Po 210 nu... [Phys. Rev. C 96, 064609] Published Mon Dec 18, 2017
    Keywords: Nuclear Reactions
    Print ISSN: 0556-2813
    Electronic ISSN: 1089-490X
    Topics: Physics
    Published by American Physical Society (APS)
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  • 6
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    Nonlinear evolution of a large-amplitude circularly polarized Alfven wave: Low beta (1994)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: The nature of turbulent cascades arising from the parametric instabilities of a monochromatic field-aligned large-amplitude circularly polarized Alfven wave is investigated via direct numerical simulation for the case of low plasma Beta and no wave dispersion. The magnetohydrodynamic code permits nonlinear couplings in the parallel direction to the ambient magnetic field and one perpendicular direction. Compressibility is included in the form of a polytropic equation of state. Anisotropic turbulent cascades, similar to those found in early incompressible two-dimensional simulations, occur after nonlinear saturation of the parallel propagating decay instability. The turbulent spectrum can be divided into three regimes: the lowest wave numbers are dominated by lower sideband remnants of the parametric process, intermediate wave numbers display nearly incompressible dynamics, and the highest wave numbers are dominated by acoustic turbulence.
    Keywords: PLASMA PHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; A7; p. 13,351-13,362
    Format: text
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  • 7
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    Nonlinear evolution of a large-amplitude circularly polarized Alfven wave: High beta (1994)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The nonlinear dynamics following saturation of the parametric instabilities of a monochromatic field-aligned large-amplitude circularly polarized Alfven wave is investigated via direct numerical simulation in the case of high plasma beta and no wave dispersion. The magnetohydrodynamic (MHD) code permits nonlinear couplings in the parallel direction to the ambient magnetic field and one perpendicular direction. Compressibility is included in the form of a polytropic equation of state. Turbulent cascades develop after saturation of two coupled oblique three-wave parametric instabilities; one of which is an oblique filamentationlike instability reported earlier. Remnants of the parametric processes, as well as of the original Alfven pump wave, persist during late nonlinear times. Nearly incompressible MHD features such as spectral anisotropies appear as well.
    Keywords: PLASMA PHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; A10; p. 19,289-19,300
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  • 8
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    The onset of Alfvenic turbulence (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: An investigation is conducted on how low-frequency MHD oscillations in a warm plasma may undergo a transition from a coherent state to one of turbulence. A driven/dissipative derivative nonlinear Schroedinger equation is derived from the fluid equations. The time evolution of an arbitrary spectrum of waves is analyzed in the case where one k-mode is unstable, with the rest damped. It is found that the transition from order to chaos in the driven/dissipative system is correlated with the existence or absence of 'breathing' solitons in the associated conservative system.
    Keywords: PLASMA PHYSICS
    Type: Physics of Fluids (ISSN 0031-9171); 30; 1371-138
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  • 9
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    Parametric instabilities of a large-amplitude circularly polarized Alfven wave - Linear growth in two-dimensional geometries (1993)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The growth of parametric instabilities, which may lead to the development of a turbulent cascade, is studied using an MHD code that permits nonlinear couplings in the parallel direction to the ambient magnetic field and one perpendicular direction. Compressibility is included in the form of a polytropic equation of state. Parametric instabilities associated with a parallel-propagating decay instability are found to dominate the low-beta case. An obliquely propagating filamentationlike instability dominates the high-beta case. The nonlinear growth of the nth harmonic of a daughter wave growing as a factor of n times the fundamental's growth rate is found in both cases. Nonlinear saturation is caused by the parallel decay instability in the low-beta case and by the oblique filamentationlike instability in the high-beta case.
    Keywords: PLASMA PHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 98; A9; p. 15,561-15,570.
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  • 10
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    Chaotic behaviour of high Mach number flows (1985)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The stability of the super-Alfvenic flow of a two-fluid plasma model with respect to the Mach number and the angle between the flow direction and the magnetic field is investigated. It is found that, in general, a large scale chaotic region develops around the initial equilibrium of the laminar flow when the Mach number exceeds a certain threshold value. After reaching a maximum the size of this region begins shrinking and goes to zero as the Mach number tends to infinity. As a result high Mach number flows in time independent astrophysical plasmas may lead to the formation of 'quasi-shocks' in the presence of little or no dissipation.
    Keywords: PLASMA PHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 148; 1 Ju
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