scholarly journals Shell evolution in neutron-rich Ge, Se, Kr and Sr nuclei within RHB approach

2020 ◽  
pp. 2050089
Author(s):  
M. El Adri ◽  
M. Oulne
Keyword(s):  
Energy Surface ◽  
Magic Number ◽  
Theoretical Models ◽  
Meson Exchange ◽  
Pairing Energy ◽  
Droplet Model ◽  
Energy Potential ◽  
Density Dependent ◽  
Number Formula ◽  
Dependent Point

The exotic even–even isotopic chains from [Formula: see text] to [Formula: see text] are investigated by means of the relativistic Hartree–Bogoliubov (RHB) approach with the explicit Density Dependent Meson-Exchange (DD-ME2) and Density-Dependent Point-Coupling (DD-PC1) models. The classic magic number [Formula: see text] is reproduced and the new number [Formula: see text] is predicted to be a robust shell closure by analysing several calculated quantities such as: two-neutron separation energies, two-neutron shell gap, neutron pairing energy, potential energy surface and neutron single particle energies. The obtained results are compared with the predictions of finite range droplet model (FRDM) and with the available experimental data. A reasonable and satisfactory agreement between the theoretical models and experiment is established.

RELATIVISTIC MEAN FIELD THEORETICAL FOUNDATION OF THE DROPLET MODEL FOR NUCLEI

2002 ◽  
Vol 11 (01) ◽  
pp. 55-65 ◽  
Author(s):  
CHUN-YUAN GAO ◽  
QI-REN ZHANG
Keyword(s):  
Mass Formula ◽  
Energy Surface ◽  
Theoretical Foundation ◽  
Mean Field Theory ◽  
Mean Field ◽  
Binding Energies ◽  
Droplet Model ◽  
Relativistic Mean Field ◽  
Theoretical Foundations ◽  
Type Mass

The binding energies per-nucleon for 1654 nuclei, whose mass numbers range from 16 to 263 and charge numbers range from 8 to 106, are calculated by the relativistic mean field theory, with finite nucleon size effect being taken into account. The calculated energy surface goes through the middle of experimental points, and the root mean square deviation for the binding energies per-nucleon is 0.08163 MeV. The numerical results may be well simulated by a droplet model type mass formula. The droplet model is therefore put on the relativistic mean field theoretical foundations.

scholarly journals Reaction Path Description and Internal-Mode Dynamics of Molecular Rearrangement in HO2

1991 ◽  
Vol 11 (3-4) ◽  
pp. 199-203 ◽  
Author(s):  
Ch. Zuhrt ◽  
L. Zülicke ◽  
F. Schneider ◽  
X. Chapuisat
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Surface Topography ◽  
Exchange Reaction ◽  
Energy Surface ◽  
Reaction Path ◽  
Theoretical Models ◽  
Internal Mode ◽  
Molecular Rearrangement

After brief general remarks and definitions for the reaction path concept in view of formulating physically transparent and computationally feasible theoretical models, the HO2 system is studied for both the bimolecular exchange reaction and the intramolecular H transfer (isomerization). The analysis includes potential energy surface topography, reaction profiles and internal-mode dynamics.

scholarly journals Ground state properties and shape evolution in Pt isotopes within the covariant density functional theory

2019 ◽  
Vol 28 (10) ◽  
pp. 1950078
Author(s):  
Y. El Bassem ◽  
M. Oulne
Keyword(s):  
Density Functional Theory ◽  
Ground State ◽  
Density Functional ◽  
Meson Exchange ◽  
Isotopic Chain ◽  
Functional Theory ◽  
Density Dependent ◽  
Covariant Density Functional Theory ◽  
Ground State Properties ◽  
Covariant Density

In this work, the ground state properties of the platinum isotopic chain, [Formula: see text]Pt are studied within the covariant density functional theory. The calculations are carried out for a large number of even–even Pt isotopes by using the density-dependent point-coupling and the density-dependent meson-exchange effective interactions. All ground state properties such as the binding energy, separation energy, two-neutron shell gap, root mean square (rms)-radii for neutrons and protons and quadrupole deformation are discussed and compared with available experimental data, and with the predictions of some nuclear models such as the Relativistic Mean Field (RMF) model with NL3 functional and the Hartree–Fock–Bogoliubov (HFB) method with SLy4 Skyrme force. The shape phase transition for Pt isotopic chain is also studied. Its corresponding total energy curves as well as the potential energy surfaces confirm the transition from prolate to oblate shapes at [Formula: see text]Pt contrary to some studies predictions and in agreement with others. Overall, a good agreement is found between the calculated and experimental results wherever available.

Neutron skin thickness of finite nuclei with finite range effective interaction in droplet model

2018 ◽  
Vol 27 (06) ◽  
pp. 1850049 ◽  
Author(s):  
M. Pal ◽  
S. Chakraborty ◽  
B. Sahoo ◽  
S. Sahoo
Keyword(s):  
Symmetry Energy ◽  
Effective Interaction ◽  
Skin Thickness ◽  
Neutron Skin ◽  
Droplet Model ◽  
Density Region ◽  
Neutron Skin Thickness ◽  
Number Formula ◽  
Energy Formula ◽  
Finite Nuclei

We analyze the relation between the symmetry energy coefficient [Formula: see text] of finite nuclei with mass number [Formula: see text] in the semi-empirical mass formula. The nuclear matter symmetry energy [Formula: see text] at reference density [Formula: see text] in the subsaturation density region can be determined by the symmetry energy [Formula: see text] and its density slope [Formula: see text] at the saturation density [Formula: see text]. From this relation, the neutron skin thickness ‘[Formula: see text]’ in finite nuclei with droplet model are correlated to the various symmetry energy parameters. A prominent role of the bulk symmetry energy [Formula: see text] to the so-called surface stiffness coefficient [Formula: see text] is observed in deriving the size of the neutron skin. Two types of neutron skins are distinguished: the “surface” and the “bulk”. The linear dependence of the neutron skin thickness for different stable nuclei ([Formula: see text]) on the slope [Formula: see text] of the symmetry energy as well as on the relative neutron excess [Formula: see text] is observed. Though the value of the surface width is found to be limited within 0.1[Formula: see text]fm, its contribution should not be neglected to measure neutron skin thickness.

Dynamical analysis for delayed virus infection models with cell-to-cell transmission and density-dependent diffusion

2020 ◽  
Vol 13 (07) ◽  
pp. 2050060
Author(s):  
Shaoli Wang ◽  
Achun Zhang ◽  
Fei Xu
Keyword(s):  
Neumann Boundary ◽  
Basic Reproductive Number ◽  
Dynamical Analysis ◽  
Reproductive Number ◽  
Asymptotically Stable ◽  
Cell Infection ◽  
Globally Asymptotically Stable ◽  
Single Strain ◽  
Density Dependent ◽  
Number Formula

In this paper, certain delayed virus dynamical models with cell-to-cell infection and density-dependent diffusion are investigated. For the viral model with a single strain, we have proved the well-posedness and studied the global stabilities of equilibria by defining the basic reproductive number [Formula: see text] and structuring proper Lyapunov functional. Moreover, we found that the infection-free equilibrium is globally asymptotically stable if [Formula: see text], and the infection equilibrium is globally asymptotically stable if [Formula: see text]. For the multi-strain model, we found that all viral strains coexist if the corresponding basic reproductive number [Formula: see text], while virus will extinct if [Formula: see text]. As a result, we found that delay and the density-dependent diffusion does not influence the global stability of the model with cell-to-cell infection and homogeneous Neumann boundary conditions.

TRITON BREAKUP AND FORMATION AT VERY LOW ENERGIES

2012 ◽  
Vol 21 (09) ◽  
pp. 1230008 ◽  
Author(s):  
H. SADEGHI
Keyword(s):  
Radiative Capture ◽  
Theoretical Models ◽  
Effective Field ◽  
Meson Exchange ◽  
Momentum Dependence ◽  
Nucleon Force ◽  
Capture Process ◽  
Low Energies ◽  
Nucleon Interactions ◽  
Three Body

Different theoretical models for two- and three-body electromagnetic currents are constructed using meson-exchange mechanisms and minimal substitution in the momentum dependence of two- and three-nucleon interactions. We review the use of effective field theory (EFT) to compute electromagnetic reactions in three-nucleon systems at very low energies. We first explain how EFT theory can be extended to incorporate the photon into the three-nucleon systems when also a three-nucleon force is acting. We also explain the predictions of the resulting EFT for neutron–deuteron radiative capture process at very low energies. In this work, a number of low-energy photonuclear observables, including neutron–deuteron radiative capture reactions and triton photodisintegration, are calculated in order to make a comparative study of the pion-less EFT results with the models based on the realistic Argonne v18(AV18) two-nucleon and Urbana IX or Tucson–Melbourne three-nucleon interactions. The calculated cross-section of neutron–deuteron radiative capture and photon polarization parameter of 3 H are in satisfactory agreement with the available experimental data.

scholarly journals Energy Landscapes, Self-Assembly and Viruses

2005 ◽  
Vol 6 (2) ◽  
pp. 107-110 ◽  
Author(s):  
D. J. Wales
Keyword(s):  
Protein Folding ◽  
Potential Energy ◽  
Potential Energy Surface ◽  
Self Assembly ◽  
Energy Surface ◽  
Genetic Material ◽  
Magic Number ◽  
Molecular Beams ◽  
Energy Landscapes ◽  
Guided Exploration

Phenomena such as protein folding, crystallisation, self-assembly, and the observation of magic number clusters in molecular beams are all the result of non-random searches. Analysis of the underlying potential energy surface may provide a unifying framework to explain how such events occur as the result of a guided exploration of the landscape. In particular, icosahedral shells composed of 12 pentagonal pyramids are found to be thermodynamically favourable and kinetically accessible when the pyramids are not too spiky and not too flat. Hence, viruses with icosahedral capsids not only minimise the genetic material required to encode the repeated subunits, but may also utilise the favourable properties of a potential energy surface that effectively directs self-assembly.

The energy landscape as a unifying theme in molecular science

2004 ◽  
Vol 363 (1827) ◽  
pp. 357-377 ◽  
Author(s):  
David J. Wales
Keyword(s):  
Potential Energy ◽  
Self Assembly ◽  
Energy Surface ◽  
Energy Landscape ◽  
Magic Number ◽  
Building Blocks ◽  
Coarse Grained ◽  
Coarse Grained Model ◽  
The Right ◽  
Molecular Science

The potential energy surface (PES) underlies most calculations of structure, dynamics and thermodynamics in molecular science. In this contribution connections between the topology of the PES and observable properties are developed for a coarse–grained model of virus capsid self–assembly. The model predicts that a thermodynamically stable, kinetically accessible icosahedral shell exists for pentameric building blocks of the right shape: not too flat and not too spiky. The structure of the corresponding PES is probably common to other systems where directed searches avoid Levinthal's paradox, such as ‘magic number’ clusters, protein folding and crystallization.

Methods of analysing competition with special reference to herbage plants: II. Effects of associate plants

1973 ◽  
Vol 81 (1) ◽  
pp. 91-98 ◽  
Author(s):  
J. Hill
Keyword(s):  
Special Reference ◽  
Present Experiment ◽  
Theoretical Models ◽  
Regression Technique ◽  
Frequency Dependent ◽  
Density Dependent ◽  
Regression Techniques ◽  
Dependent Density

SummaryAn examination of the role played by associate plants in conditioning the behaviour of a competitor was carried out on a diallel arrangement of five perennial ryegrasa genotypes using regression techniques similar to those devised for the analysis of genotype-environment interactions. By far the largest proportion of the significant genotype x associate interaction could be ascribed to differences between the slopes of the fitted regression lines, with the three long-leaved genotypes (A, C and E)having the highest slopes and hence being the most sensitive to changes in the associate environment. Significant departures from the fitted regression lines occurred, however, but these could be traced solely to genotype C.Theoretical models capable of identifying those conditions under which 50:50 mixtures may be expected, first, to exceed the average of their component monocultures, and secondly, to surpass the better monoculture, were developed. Applying these models to the present experiment confirms that the performance of the 50:50 mixtures generally exceeds the monoculture average, but rarely surpasses the better monoculture.The scope of the regression technique was broadened to incorporate the 75:25 and 25: 75 mixtures, thereby revealing that the response of the two strongest competitors (C and E) is frequency dependent. Density dependent effects were also uncovered in this material, with genotype C the strongest competitor, being particularly noteworthy in this respect. The role of this regression technique in the development of new and highly productive mixtures is briefly discussed.

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