Static and dynamical aspects of nuclear systems are described through an extended time-dependent mean-field approach. The foundations of the formalism are presented, with highlights on the estimation of average values and their corresponding dispersions. In contrast to semiclassical transport models, the particular interest of this description lies on its intrinsic quantal character. The reliability of this approach is discussed by means of stopping-sensitive observables analysis in heavy-ion collisions in the range of 20 to 120 MeV per nucleon.

We propose new theoretical approaches in order to introduce fluctuations in an Extended-TDHF description. On the one side, a prescription for estimating the dispersions in one-body observables related to small amplitude fluctuations of the statistical kind is proposed. On the other side, the characterization of large amplitude density fluctuations generated by multiparticle correlations is addressed through a stochastic extension yielding Langevin-type fluctuations. Applications to nuclear collisions at incident energies around the Fermi energy are presented.

The potential energy governing the shape and the entrance and decay channels of the 12C, 16O, 20Ne, 24Mg, and 32S 4n-nuclei has been determined within a generalized liquid drop model. Different three-dimensional and planar shapes have been investigated: linear chain, triangle, square, tetrahedron, pentagon, trigonal bipyramid, square pyramid, hexagon, octahedron, octogon and cube. The rms radii of the linear chains are higher than the experimental rms radii of the ground states. The binding energies of the planar shapes at the contact point are lower than the ones of the three-dimensional configurations. The α particle plus A-4 daughter configuration leads always to the lowest potential barrier relatively to the sphere configuration.

Within a liquid drop model the energy of the C-12, O-16, 20 Ne, Mg-24 and S-32 4n-nuclei has been calculated within different con figurations of alpha-molecules : linear chain, triangle, square, tetrahedron, pentagon, trigonal bipyramid, square pyramid, hexagon, octahedron, octagon and cube. The potential barriers governing the decay and entrance channels via alpha emission or absorption as well as the potential barriers of other possible binary and ternary reactions have been compared. The rms radii of the linear chains do not correspond to the experimental rms radii of the ground states. The binding energies of the three-dimensional molecules at the nascent point of the fragments are higher than the ones of the planar configurations. The A-4 daughter plus alpha particle configurations have always the lowest potential energy.

Within a liquid drop model the energy of the12C,16O,20Ne,24Mg and32S 4n-nuclei has been calculated within different configurations of α-molecules : linear chain, triangle, square, tetrahedron, pentagon, trigonal bipyramid, square pyramid, hexagon, octahedron, octagon and cube. The potential barriers governing the decay and entrance channels via α emission or absorption as well as the potential barriers of other possible binary and ternary reactions have been compared. The rms radii of the linear chains do not correspond to the experimental rms radii of the ground states. The binding energies of the three-dimensional molecules at the nascent point of the fragments are higher than the ones of the planar configurations. The A-4 daughter plus α particle configurations have always the lowest potential energy.

With the semiclassical Landau-Vlasov transport model studied is the stopping observable $R_E$, the energy-based isotropy ratio, for the $^{129}$Xe\,+\,$^{120}$Sn reaction at beam energies spanning 12$A$ to 100$A$ MeV. Investigated is the impact of the non-locality of the nuclear mean field, of the in-medium modified nucleon-nucleon ($NN$) cross-section and of the reaction centrality. A fixed set of model parameters yield the $R_E$ values that favourably compares with the experimental ones but only for energies below the Fermi energy $E_F$. Above $E_F$ the agreement is readily possible but by a smooth evolution with energy of the parameter that controls the in-medium modification of $NN$ cross-section. By confronting the simulation correction factor ${\cal F}$ to be applied to the free $NN$ cross-section with the one which has been deduced from experimental data [Phys. Rev. C\,{\bf 90}, 064602 (2014)] one infers that the zero-range mean field almost entirely reproduces it. Also, in accordance with what has been deduced from experimental data, around $E_F$ a strong reduction of the free $NN$ cross-section is found. In order to test the impact of sampling central collisions by multiplicity an event generator (HIPSE) was used. One obtains that high multiplicity events are spread over a broad impact parameter range but it turns out that this has a small effect on the observable $R_E$ and, thus, on ${\cal F}$as well.

With the semiclassical Landau-Vlasov transport model we studied the stopping observable $R_E$, the energy-based isotropy ratio, for the $^{129}$Xe\,+\,$^{120}$Sn reaction at beam energies spanning 12$A$ to 100$A$ MeV. We investigated the impacts of the nonlocality of the nuclear mean field, of the in-medium modified nucleon-nucleon ($NN$) cross section and of the reaction centrality. A fixed set of model parameters yields $R_E$ values that favorably compare with the experimental ones, but only for energies below the Fermi energy $E_F$. Above $E_F$ agreement is readily possible, but by a smooth evolution with energy of the parameter that controls the in-medium modification of $NN$ cross section. By comparing the simulation correction factor ${\cal F}$ applied to the free $NN$ cross section with the one deduced from experimental data [Phys.\ Rev.\ C\,{\bf 90}, 064602 (2014)], we infer that the zero-range mean field almost entirely reproduces it. Also, in accordance with what has been deduced from experimental data, around $E_F$ a strong reduction of the free $NN$ cross section is found. In order to test the impact of sampling central collisions by multiplicity an event generator (HIPSE) was used. We obtain that high multiplicity events are spread over a broad impact parameter range, but it turns out that this has a small effect on the observable $R_E$ and, thus, on ${\cal F}$ as well.

With the semiclassical Landau-Vlasov transport model studied is the stopping observable $R_E$, the energy-based isotropy ratio, for the $^{129}$Xe,+,$^{120}$Sn reaction at beam energies spanning 12$A$ to 100$A$ MeV. Investigated is the impact of the non-locality of the nuclear mean field, of the in-medium modified nucleon-nucleon ($NN$) cross-section and of the reaction centrality. A fixed set of model parameters yield the $R_E$ values that favourably compares with the experimental ones but only for energies below the Fermi energy $E_F$. Above $E_F$ the agreement is readily possible but by a smooth evolution with energy of the parameter that controls the in-medium modification of $NN$ cross-section. By confronting the simulation correction factor ${cal F}$ to be applied to the free $NN$ cross-section with the one which has been deduced from experimental data [Phys. Rev. C,{bf 90}, 064602 (2014)] one infers that the zero-range mean field almost entirely reproduces it. Also, in accordance with what has been deduced from experimental data, around $E_F$ a strong reduction of the free $NN$ cross-section is found. In order to test the impact of sampling central collisions by multiplicity an event generator (HIPSE) was used. One obtains that high multiplicity events are spread over a broad impact parameter range but it turns out that this has a small effect on the observable $R_E$ and, thus, on ${cal F}$as well.

In heavy-ions collisions different observables have been studied in order to get an insight about dissipative processes taking place in the excited nuclear system. Among them, we can focus on the ratio between the transverse and longitudinal kinetic energy components, or stopping power R-E. A substancial reduction of this quantity has been recently evidenced by the INDRA collaboration at incident energies between 32 and 100 A MeV, for various symmetric systems. In this work, the impact of sigma(nn) on the stoping power R-E is studied in the framework of the microscopic DYWAN model. Calculations have been performed in Xe+Sn central collisions at incident energies between 45 and 100 A MeV, where the theoretical values are shown to be more sensitive to sigma(nn). They are compared with experimental data and with the results of the semiclassical Landau-Vlasov model.

We report on a systematics of fusion cross section data at energies above the reaction threshold to those of disappearance of fusion process. By an appropriate scaling of both cross sections and energy, a fusion excitation function common to all the data points is established. A universal description of the fusion excitation function relying on basic nuclear concepts is proposed and its dependence on the reaction cross section used for the cross section normalization is discussed.

A systematics of over 300 complete and incomplete fusion cross section data points covering energies beyond the barrier for fusion is presented. Owing to a usual reduction of the fusion cross sections by the total reaction cross sections and an original scaling of energy, a fusion excitation function common to all the data points is established. A universal description of the fusion exci- tation function relying on basic nuclear concepts is proposed and its dependence on the reaction cross section used for the cross section normalization is discussed. The pioneering empirical model proposed by Bass in 1974 to describe the complete fusion cross sections is rather successful for the incomplete fusion too and provides cross section predictions in satisfactory agreement with the observed universality of the fusion excitation function. The sophisticated microscopic transport DYWAN model not only reproduces the data but also predicts that fusion reaction mechanism disappears due to weakened nuclear stopping power around the Fermi energy.

The energies of the C-12,O-16,Ne-20,Mg-24, and S-32 4n nuclei have been determined within a generalized liquid drop model and assuming different planar and three-dimensional shapes of the alpha molecules: linear chain, triangle, square, tetrahedron, pentagon, trigonal bipyramid, square pyramid, hexagon, octahedron, octagon, and cube. The potential barriers governing the entrance and decay channels via alpha absorption or emission as well as more symmetric binary and ternary reactions have been compared. The rms radii of the linear chains differ from the experimental rms radii of the ground states. The binding energies of the three-dimensional shapes at the contact point are higher than the ones of the planar configurations. The alpha particle plus A-4 daughter configuration leads always to the lowest potential barrier. The binding energy can be reproduced within the sum of the binding energy of n alpha particles plus the number of bonds multiplied by 2.4 MeV or by the sum of the binding energies of one alpha particle and the daughter nucleus plus the Coulomb energy and the proximity energy.

The energies of the $^{12}\mathrm{C},^{16}\mathrm{O},^{20}\mathrm{Ne},^{24}\mathrm{Mg},$ and $^{32}\mathrm{S} 4n$ nuclei have been determined within a generalized liquid drop model and assuming different planar and three-dimensional shapes of the $\ensuremath{\alpha}$ molecules: linear chain, triangle, square, tetrahedron, pentagon, trigonal bipyramid, square pyramid, hexagon, octahedron, octagon, and cube. The potential barriers governing the entrance and decay channels via $\ensuremath{\alpha}$ absorption or emission as well as more symmetric binary and ternary reactions have been compared. The rms radii of the linear chains differ from the experimental rms radii of the ground states. The binding energies of the three-dimensional shapes at the contact point are higher than the ones of the planar configurations. The $\ensuremath{\alpha}$ particle plus A-4 daughter configuration leads always to the lowest potential barrier. The binding energy can be reproduced within the sum of the binding energy of $n \ensuremath{\alpha}$ particles plus the number of bonds multiplied by 2.4 MeV or by the sum of the binding energies of one $\ensuremath{\alpha}$ particle and the daughter nucleus plus the Coulomb energy and the proximity energy.

Presented is a universal description of the generalized fusion excitation function which indicates that the fusion reaction mechanism should vanish at center-of-mass energy per nucleon of about 13 MeV/nucleon independently of the specific heavy-ion reaction system. Placing reliance on this result and comforted by semiclassical transport model simulations we suggest that the proposed persistence of the incomplete fusion cross sections in the measurement of the 14N induced reactions on heavy targets at beam energies between 100A and 155A MeV should be attributed to a geometrical participant-spectator-like reaction mechanism.

We report on the comprehensive systematics of nearly 400 fusion-evaporation and/or fusion-fission cross section data for a very large variety of systems over an energy range similar to 3A to 155A MeV. Scaled by the reaction cross section and expressed as a function of the center-of-mass energy per nucleon, the fusion cross section displays a universal behavior. Within experimental errors, this behavior does not depend on system mass, mass asymmetry, or system isospin. The deduced homographic functional dependence for complete and summed complete and incomplete fusion excitation functions is derived from basic strong absorption model formulas for reaction cross sections and allows us to draw the main properties of these functions. The limiting energy for the complete fusion and the main characteristics (onset, maximum, and extinction) of the incomplete fusion excitation functions are determined. The complete fusion reaction process disappears around 6.5 MeV/nucleon and the incomplete one disappears at about 13 MeV/nucleon in the center-of-mass frame. The regularity in fusion data is particularly obvious for the evaporation-residue subset of the data ensemble. Adding the fusion-fission data component does not alter the general data trend but somewhat obscures it owing to the larger uncertainty and/or possible normalization problems.

We report on a comprehensive systematics of fusion-evaporation and/or fusion-fission cross sections for a very large variety of systems over an energy range 4A-155A MeV. Scaled by the reaction cross sections, fusion cross sections do not show a universal behavior valid for all systems although a high degree of correlation is present when data are ordered by the system mass asymmetry. For the rather light and close to mass-symmetric systems the main characteristics of the complete and incomplete fusion excitation functions can be precisely determined. Despite an evident lack of data above 15A MeV for all heavy systems the available data suggests that geometrical effects could explain the persistence of incomplete fusion at incident energies as high as 155A MeV.

A meticulous study of nearly 300 fusion-evaporation cross-section data reveals that, when properly scaled, fusion excitation function complies with a universal homographic law which is, within experimental errors, reaction system independent. From such complete and summed complete and incomplete fusion excitation functions are extracted the limiting energy for the complete fusion and the main characteristics (onset, maximum and vanishing) of the incomplete fusion. The DYWAN microscopic transport model correctly predicts the incomplete fusion cross-section for incident energies and suggests that the nuclear transparency is at the origin of fusion disappearance.

Semiclassical transport simulation of nucleus-nucleus collisions for the range of incident energy from about the Fermi energy up to a few hundred MeV per nucleon evidences that the maximal excitation energy put into a nuclear system during the early compact stage of heavy-ion reaction is a constant fraction of the center-of-mass available energy of the system. Analysis of experimental data without presuming reaction mechanism dominating the collision process on the best corroborates the found constancy of energy partition in central heavy-ion reactions.

The dynamics of infinite nuclear matter in the conditions of density and temperature expected in the outermost layers of neutron stars is studied in the framework of a microscopic time-dependent mean-field approach around zero temperature. Dynamical processes in inhomogeneous nuclear matter are studied using a large number of nucleons in numerical simulations without any assumptions on the morphology of nuclear matter. The occurrence of exotic structures when varying internal conditions as densities, nuclear species and elementary cell symmetries is investigated. The corresponding structures are studied in terms of a phase diagram in density space evidencing some sensitivity to the isospin-dependent part of the equation of state.

Neutron Stars are natural laboratories where fundamental properties of matter under extreme conditions can be explored. Modern nuclear physics input as well as many-body theories are valuable tools which may allow us to improve our understanding of the physics of those compact objects.In this work the occurrence of exotic structures in the outermost layers of neutron stars is investigated within the framework of a microscopic model. In this approach the nucleonic dynamics is described by a time-dependent mean field approach at around zero temperature. Starting from an initial crystalline lattice of nuclei at subnuclear densities the system evolves toward a manifold of self-organized structures with different shapes and similar energies. These structures are studied in terms of a phase diagram in density and the corresponding sensitivity to the isospin-dependent part of the equation of state and to the isotopic composition is investigated.