The nuclear mean-field model based on Skyrme forces or related density functionals has found widespread application to the description of nuclear ground states, collective vibrational excitations, and heavy-ion collisions. The code Sky3D solves the static or dynamic equations on a three-dimensional Cartesian mesh with isolated or periodic boundary conditions and no further symmetry assumptions. Pairing can be included in the BCS approximation for the static case. The code is implemented with a view to allow easy modifications for including additional physics or special analysis of the results

We present a study of fusion cross sections using a new generation Time-Dependent Hartree-Fock (TDHF) code which contains no approximations regarding collision geometry and uses the full Skyrme interaction, including all of the time-odd terms. In addition, the code uses the Basis-Spline collocation method for improved numerical accuracy. A comparative study of fusion cross sections for 16 O + 16,28 O is made with the older TDHF results and experiments. We present results using the modern Skyrme forces and discuss the influence of the new terms present in the interaction. PACS numbers: 21.60.-n,21.60.Jz

We show that dynamical deformation effects play an important role in fusion reactions involving the 64 Ni nucleus, in particular the 64 Ni+ 132 Sn system. We calculate fully microscopic interaction potentials and the corresponding subbarrier fusion cross sections.

Although the overall time-scale for nuclear fission is long, suggesting a slow process, rapid shape evolution occurs in its later stages near scission. Theoretical prediction of the fission fragments and their characteristics are often based on the assumption that the internal degrees of freedom are equilibrated along the fission path. However, this adiabatic approximation may break down near scission. This is studied for the symmetric fission of $^{258,264}$Fm. The non-adiabatic evolution is computed using the time-dependent Hartree-Fock method, starting from an adiabatic configuration where the fragments have acquired their identity. It is shown that dynamics has an important effect on the kinetic and excitation energies of the fragments. The vibrational modes of the fragments in the post-scission evolution are also analyzed.Comment: 5 pages, 4 figures. Accepted for publication in Phys. Rev. C - Rapid Communitatio

We investigate neutrino-driven convection in core collapse supernovae and its ramifications for the explosion mechanism. We begin with an "optimistic" postbounce model in two important respects: (1) we begin with a 15 M ⊙ precollapse model, which is representative of the class of stars with compact iron cores; (2) we implement Newtonian gravity. Our precollapse model is evolved through core collapse and bounce in one dimension using multigroup (neutrino-energy-dependent) flux-limited diffusion (MGFLD) neutrino transport and Newtonian Lagrangian hydrodynamics, providing realistic initial conditions for the postbounce convection and evolution.Our two-dimensional simulation began at 12 ms after bounce and proceeded for 500 ms.We couple two-dimensional (PPM) hydrodynamics to precalculated one-dimensional MGFLD neutrino transport. (The neutrino distributions used for matter heating and deleptonization in our 2D run are obtained from an accompanying 1D simulation. The accuracy of this approximation is assessed.) For the moment we sacrifice dimensionality for realism in other aspects of our neutrino transport. MGFLD is an implementation of neutrino transport that simultaneously (a) is multigroup and (b) simulates with sufficient realism the transport of neutrinos in opaque, semitransparent, and transparent regions. Both are crucial to the accurate determination of postshock neutrino heating, which sensitively depends on the luminosities, spectra, and flux factors of the electron neutrinos and antineutrinos emerging from their respective neutrinospheres.By 137 ms after bounce, we see neutrino-driven convection rapidly developing beneath the shock. By 212 ms after bounce, this convection becomes large-scale, characterized by higher-entropy, expanding upflows and denser, lower-entropy, finger-like downflows. The upflows reach the shock and distort it from sphericity. The radial convection velocities at this time become supersonic just below the shock, reaching magnitudes in excess of 10 9 cm/sec. Eventually, however, the shock recedes to smaller radii, and at ∼500 ms after bounce there is no evidence in our simulation of an explosion or of a developing explosion.Our angle-averaged density, entropy, electron fraction, and radial velocity profiles in our below the electron neutrino and antineutrino gain radii, above which the neutrino luminosities are essentially constant (i.e., the neutrino sources are entirely enclosed), in an effort to assess how spherically symmetric our neutrino sources remain during our 2D evolution, and therefore, to assess our use of precalculated 1D MGFLD neutrino distributions in calculating the matter heating and deleptonization. We find no differences below the neutrinosphere radii, and between the neutrinosphere and gain radii, no differences with obvious ramifications for the supernova outcome.We note that the interplay between neutrino transport and convection below the neutrinospheres is a delicate matter, and is discussed at greater length in another paper (Mezzacappa et al. 1997a).However, ...