摘要:

We study nonlinear response in weakly coupled nonequilibrium&fgr;4theory in the context of both classical transport theory and real time quantum field theory, based on a generalized Kubo formula which we derive. A novel connection between these two approaches is established which provides a diagrammatic interpretation of the Boltzmann equation. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1427462

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

The stochastic one-body transport theory in non-relativistic framework is briefly reviewed, and a coherent damping mechanism arising from the coupling between the mean-field fluctuations and the single-particle motion is discussed. For small amplitude fluctuations, the coherent mechanism appears as a particle-phonon collision term in the transport equation for the average density matrix, which play a dominant role in damping of giant resonance excitations and nuclear collective motion at low energies. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1427463

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

Classical lattice field theories are studied in non-equilibrium steady states from first principles by placing them in strong thermal gradients. The breakdown of local equilibrium as well as general observables is quantified. We find that linear response predictions are violated at the same rate as the breakdown of local equilibrium, and that there is no threshold for this behavior. Further, the equation of state develops non-local contributions even in theories with bulk behavior in the non-equilibrium steady state. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1427464

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

A dynamical framework for synthesis of the superheavy elements is presented, where fusion process is treated by fluctuation-dissipation dynamics with Langevin equations in two steps; approaching phase and shape evolution. Preliminary results are given for residue cross sections ofZ=114with48Ca+244Puentrance channel, combining the statistical decay calculations. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1427465

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

In the late 70’s the time-dependent Hartree-Fock (TDHF) approximation originally proposed by Bonche, Koonin, and Negele [1] was used in a number of studies of heavy-ion collisions. These calculations yielded a lot of insight into the reaction dynamics, explaining such phenomena as neck formation and neck rapture and the collective excitations of the fragments in a natural way. There were a number of limitations, however, which decreased interest in the method: while the energy losses in deep-inelastic reactions could be understood semiquantitatively, there was insufficient energy loss for central collisions, leading to a window of deep-inelastic reactions at small angular momenta within the fusion region. This raised the question of whether two-body collisions can be neglected. Also, because of computer limitations at that time, most calculations were done in axial symmetry and the spin-orbit coupling could not be included. In later work, a limited exploration of TDHF with spin-orbit coupling seemed to indicate that this may provide sufficient additional dissipation. We believe that present computer capabilities are sufficient to use TDHF in fully three-dimensional geometry and including the spin-orbit force. This will for the first time allow the investigation of collisions of deformed nuclei. The theory will be explained and first results for collisions of deformed light nuclei will be presented. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1427466

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

Examples of important recent achievements in the study of multinucleon transfer reactions at Coulomb barrier energies are presented. The unambiguous identification of transfer products up to the pick-up of six neutrons and the stripping of six-eight protons allows to investigate into detail the degrees of freedom acting in the transfer process. This is important also for &ggr; spectroscopic studies and for future research to be done with radioactive beams. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1427467

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

We discuss the response of metal clusters subject strong electromagnetic fields in the framework of density functional theory. This allows a fully nonadiabatic treatment of both electronic and ionic degrees of freedom. We give a few general properties of metal clusters which can be accessed with this kind of nonadiabatic approaches and we present an example of application of a metal cluster subject to an intense laser field. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1427468

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

We present calculations of fission potential energy surface based on Strutinsky’s prescription for realistic 5-parameter shape parametrization of the fissioning nucleus. The determination of the saddle points in this 5-dimensional potential energy surface was performed directly. The calculated fission saddle points present typical feature that most of the actinide nuclei have the lowest two saddle points, one is mass-symmetric and the other is mass-asymmetric, separated by a ridge. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1427469

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

Now-a-days, many fields of science are seemed to share the same interests as to explore the dynamics ofevolution of matter, which intends to make clear what dynamical relations are there between different strata or different levels of the nature. Relations between the “macroscopic” and “microscopic” effects, between the “classical” and “quantum” dynamics, between the dynamics and thermodynamics and so on are basic subjects to explain how the nature evolutes from one stratum to the next stratum. As an example, the nucleus provides us with a very nice benchmark field to explore the above stated subjects, because it shows a coexistence of “macroscopic” and “microscopic” effects in association with various “phase transitions,” and a mutual relation between “classical” and “quantum” effects related with the macro-level and micro-level variables, respectively. At certain energy region, the nucleus exhibits some statistical aspects which are associated with dissipation phenomena well described by the phenomenological transport equation. In this talk, a few topical subjects undertaken in our group and future problems will be discussed by putting special emphasis on clarifying the dynamics ofevolution of matter. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1427470

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

Isovector dipole resonances in the oxygen isotopes18∼24Oand fusion reactions of16O+16Oare studied using an extended version of the time-dependent Hartree-Fock theory known as the time-dependent density-matrix theory (TDDM). A newly developed TDDM program which includes spin-orbit force in a mean-field potential is used. Low-lying dipole strength in the oxygen isotopes is compared with experimental data and also with a shell-model calculation. It is found that the observed isotope dependence of low-lying dipole strength is reproduced in TDDM when the strength of the residual interaction is appropriately chosen. For the fusion reactions, it is found that the dissipation of translational energy due to two-body collisions is small when spin-orbit force is included in the mean-field potential. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1427471

出版商:AIP    

年代:1901

数据来源: AIP