ENERGY DISSIPATION IN FUSION REACTIONS FROM DYNAMICAL MEAN-FIELD THEORY

2009 ◽  
Vol 18 (10) ◽  
pp. 2114-2118 ◽  
Author(s):  
KOUHEI WASHIYAMA ◽  
DENIS LACROIX
Keyword(s):  
Energy Dissipation ◽  
Degrees Of Freedom ◽  
Center Of Mass ◽  
Mean Field Theory ◽  
Mean Field ◽  
Fusion Reactions ◽  
Simple Estimate ◽  
Hartree Fock ◽  
Center Of Mass Energy ◽  
Body Energy

Nucleus-nucleus interaction potentials and friction coefficients associated with one-body energy dissipation in the entrance channel of fusion reactions are extracted from the microscopic time-dependent Hartree-Fock theory. They show center-of-mass energy dependence close to the Coulomb barrier energy. This dependence indicates dynamical reorganization of internal degrees of freedom. We give a simple estimate of excitation energy from microscopic nucleon exchange.

scholarly journals Newtonian dynamics of imaginary time-dependent mean field theory

2021 ◽  
Vol 252 ◽  
pp. 05001
Author(s):  
Aldo Bonasera
Keyword(s):  
Cross Sections ◽  
Classical Model ◽  
Mean Field Theory ◽  
Mean Field ◽  
Time Dependent ◽  
Fusion Reactions ◽  
Model Calculations ◽  
Hartree Fock ◽  
Direct Data ◽  
Path Integral Method

A Time Dependent Hartree-Fock (TDHF) based classical model is applied to sub-barrier fusion reactions using the Feynman Path Integral Method (FPIM). The fusion cross-sections and modified astrophysical S*-factors are calculated for the 12C+12C reactions and compared to direct and indirect experimental results. Different channels cross-sections are estimated from the statistical decay of the compound nucleus. A good agreement with the direct data is found. We suggest a complementary observable given by the (imaginary) action A easily derived from theory and experiments. When properly normalized by the action in the Gamow limit it has an upper value of 1 at zero beam energies. It becomes negative at the Coulomb barrier which is Vcb=5.05±0.05MeV from direct data and Vcb=5.5MeV from model calculations.

scholarly journals RELATIVE MOTION CORRECTION TO FISSION BARRIERS

2008 ◽  
Vol 17 (01) ◽  
pp. 151-159 ◽  
Author(s):  
J. SKALSKI
Keyword(s):  
Relative Motion ◽  
Cluster Model ◽  
Motion Correction ◽  
Mean Field Theory ◽  
Mean Field ◽  
Ternary Fission ◽  
Skyrme Interaction ◽  
Hartree Fock ◽  
Fission Barriers ◽  
The Mean

We discuss the effect of kinetic energy of the relative motion becoming spurious for separate fragments on the selfconsistent mean-field fission barriers. The treatment of the relative motion in the cluster model is contrasted with the necessity of a simpler and approximate approach in the mean-field theory. A scheme of the energy correction to the Hartree-Fock is proposed. The results obtained with the effective Skyrme interaction SLy 6 show that the correction, previously estimated as ~ 8 MeV in A = 70 - 100 nuclei, amounts to 4 MeV in the medium heavy nucleus 198 Hg and to null in 238 U . However, the corrected barrier implies a shorter fission half-life of the latter nucleus. The same effect is expected to lower barriers for multipartition (i.e. ternary fission, etc) and make hyperdeformed minima less stable.

scholarly journals Evening out the spin and charge parity to increase $${T}_{c}$$ in $${{\rm{Sr}}}_{2}{{\rm{RuO}}}_{4}$$

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Swagata Acharya ◽  
Dimitar Pashov ◽  
Cédric Weber ◽  
Hyowon Park ◽  
Lorenzo Sponza ◽  
...  
Keyword(s):  
Critical Temperature ◽  
Degrees Of Freedom ◽  
Mean Field Theory ◽  
Mean Field ◽  
Spin Fluctuations ◽  
Charge Fluctuations ◽  
Ab Initio Theory ◽  
Charge Parity ◽  
Local Correlations ◽  
Critical Temperature Tc

AbstractUnconventional superconductivity in $${{\rm{Sr}}}_{2}{{\rm{RuO}}}_{4}$$Sr2RuO4 has been intensively studied for decades. However, the nature of pairing continues to be widely debated. Here we develop a detailed ab initio theory, coupling quasiparticle self-consistent GW approximation with dynamical mean field theory (DMFT), including both local and non-local correlations to address the subtle interplay among spin, charge and orbital degrees of freedom. We report that the superconducting instability has multiple triplet and singlet components. In the unstrained case the triplet eigenvalues are larger than the singlets. Under uniaxial strain, the triplet eigenvalues drop and the singlet components increase. This is concomitant with our observation of spin and charge fluctuations shifting closer to wave-vectors favoring singlet pairing. We identify a complex mechanism where charge fluctuations and spin fluctuations co-operate in the even-parity channel under strain leading to increment in critical temperature (Tc), thus proposing a novel mechanism for pushing the frontier of critical temperature (Tc) in unconventional ‘triplet’ superconductors.

scholarly journals Extraction of nucleus-nucleus potential and energy dissipation from dynamical mean-field theory

2009 ◽  
Author(s):  
Kouhei Washiyama ◽  
Denis Lacroix ◽  
K. Ernst Rehm ◽  
Birger B. Back ◽  
Henning Esbensen ◽  
...  
Keyword(s):  
Field Theory ◽  
Energy Dissipation ◽  
Mean Field Theory ◽  
Mean Field ◽  
Dynamical Mean Field Theory

VERTEX CORRECTIONS IN THE NUCLEAR SCHWINGER–DYSON FORMALISM

2002 ◽  
Vol 11 (04) ◽  
pp. 321-333 ◽  
Author(s):  
MASAHIRO NAKANO ◽  
HIROYUKI MATSUURA ◽  
TAISUKE NAGASAWA ◽  
KEN-ICHI MAKINO ◽  
NOBUO NODA ◽  
...  
Keyword(s):  
Field Theory ◽  
Correlation Energy ◽  
Mean Field Theory ◽  
Mean Field ◽  
The Other ◽  
Vertex Correction ◽  
Hartree Fock ◽  
Vertex Corrections ◽  
Negative Correlation Energy ◽  
Self Consistent

We develop the Nuclear Schwinger–Dyson (NSD) formalism to include the effects of ladder diagrams by modifying the vertex. In this extension, the NSD equation sums up both ring diagrams and ladder diagrams self-consistently. The results are compared with mean field theory, Hartree Fock and bare-vertex NSD calculations. It is shown that the vertex correction is important from the following viewpoints. First, the vertex correction greatly modifies the meson propagators, and we can avoid the ghost-pole from meson propagators in a self-consistent way. Secondly, it gives a large negative correlation-energy compared with the other calculations; as a result, it gives a softer equation of state which is preferable according to the experimental data.

RECENT APPLICATIONS OF THE DMRG METHOD

2006 ◽  
Vol 20 (19) ◽  
pp. 2624-2635
Author(s):  
KAREN HALLBERG
Keyword(s):  
Degrees Of Freedom ◽  
Mean Field Theory ◽  
Mean Field ◽  
Finite Size ◽  
Strongly Correlated Systems ◽  
Strongly Correlated ◽  
Correlated Systems ◽  
Infinite Dimensional ◽  
Low Dimensional ◽  
Time Dependent Problems

Since its inception, the DMRG method has been a very powerful tool for the calculation of physical properties of low-dimensional strongly correlated systems. It has been adapted to obtain dynamical properties and to consider finite temperature, time-dependent problems, bosonic degrees of freedom, the treatment of classical problems and non-equilibrium systems, among others. We will briefly review the method and then concentrate on its latest developments, describing some recent successful applications. In particular we will show how the dynamical DMRG can be used together with the Dynamical Mean Field Theory (DMFT) to solve the associated impurity problem in the infinite-dimensional Hubbard model. This method is used to obtain spectral properties of strongly correlated systems. With this algorithm, more complex problems having a larger number of degrees of freedom can be considered and finite-size effects can be minimized.

Nuclear structure and decay properties of Nd isotopes

2018 ◽  
Vol 27 (07) ◽  
pp. 1850059
Author(s):  
M. Ouhachi ◽  
M. R. Oudih ◽  
M. Fellah ◽  
N. H. Allal
Keyword(s):  
Mean Field Theory ◽  
Mean Field ◽  
Drip Line ◽  
Binding Energies ◽  
Neutron Drip Line ◽  
Nd Isotopes ◽  
Decay Modes ◽  
Hartree Fock ◽  
Relativistic Mean Field ◽  
Decay Properties

Using the Hartree–Fock–Bogoliubov mean-field theory, the ground-state structural and decay properties of Nd isotopes are investigated from the proton-rich side up to the neutron drip-line. Quantities such as binding energies per nucleon, one and two-neutron separation energies, rms charge radii, and quadrupole deformation parameters have been calculated. Compared with the relativistic mean-field results, the present calculations are in better agreement with the available experimental data. The results show clearly the signature of a shape transition at [Formula: see text] and an abrupt increase in the deformation near the neutron drip-line. Further, the possible decay modes like alpha, cluster and [Formula: see text]-decay are analyzed in a unified fission model and phenomenological formulas. Overall, a good agreement is achieved between the calculated and experimental [Formula: see text]-values and half-lives wherever available. The most likely decay modes are thus identified throughout the isotopic chain.

scholarly journals The valence-fluctuating ground state of plutonium

2015 ◽  
Vol 1 (6) ◽  
pp. e1500188 ◽  
Author(s):  
Marc Janoschek ◽  
Pinaki Das ◽  
Bismayan Chakrabarti ◽  
Douglas L. Abernathy ◽  
Mark D. Lumsden ◽  
...  
Keyword(s):  
Ground State ◽  
Degrees Of Freedom ◽  
Mean Field Theory ◽  
Mean Field ◽  
Complex Materials ◽  
Theoretical Understanding ◽  
Electronic Correlations ◽  
Valence Fluctuations ◽  
Electronic Configurations ◽  
Control Complex

A central issue in material science is to obtain understanding of the electronic correlations that control complex materials. Such electronic correlations frequently arise because of the competition of localized and itinerant electronic degrees of freedom. Although the respective limits of well-localized or entirely itinerant ground states are well understood, the intermediate regime that controls the functional properties of complex materials continues to challenge theoretical understanding. We have used neutron spectroscopy to investigate plutonium, which is a prototypical material at the brink between bonding and nonbonding configurations. Our study reveals that the ground state of plutonium is governed by valence fluctuations, that is, a quantum mechanical superposition of localized and itinerant electronic configurations as recently predicted by dynamical mean field theory. Our results not only resolve the long-standing controversy between experiment and theory on plutonium’s magnetism but also suggest an improved understanding of the effects of such electronic dichotomy in complex materials.

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