D. Kiderlen | Searcharxiv

arXiv1997

Fragments in Gaussian Wave-Packet Dynamics with and without Correlations

Generalization of Gaussian trial wave functions in quantum molecular dynamics models is introduced, which allows for long-range correlations characteristic for composite nuclear fragments. We demonstrate a significant improvement in the description of light fragments with the correlations. Utilizing either type of Gaussian wave functions, with or without correlations, however, we find that we cannot describe fragment formation in a dynamic situation. Composite fragments are only produced in simulations if these fragments are present as clusters in the substructure of original nuclei. The difficulty is traced to the delocalization of wave functions during emission. Composite fragments are produced abundantly in the Gaussian molecular dynamics in the limit hbar -> 0.

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arXiv1997

Statistical fluctuations for the fission process on its decent from saddle to scission

We reconsider the importance of statistical fluctuations for fission dynamics beyond the saddle in the light of recent evaluations of transport coefficients for average motion. The size of these fluctuations are estimated by means of the Kramers-Ingold solution for the inverted oscillator, which allows for an inclusion of quantum effects.

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arXiv1997

A self-consistent treatment of damped motion for stable and unstable collective modes

We address the dynamics of damped collective modes in terms of first and second moments. The modes are introduced in a self-consistent fashion with the help of a suitable application of linear response theory. Quantum effects in the fluctuations are governed by diffusion coefficients D_{μν}. The latter are obtained through a fluctuation dissipation theorem generalized to allow for a treatment of unstable modes. Numerical evaluations of the D_{μν} are presented. We discuss briefly how this picture may be used to describe global motion within a locally harmonic approximation. Relations to other methods are discussed, like "dissipative tunneling", RPA at finite temperature and generalizations of the "Static Path Approximation".

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arXiv1997

A self-consistent treatment of the dynamics of stable and unstable collective modes

We address the dynamics of damped collective modes in terms of first and second moments. The modes are introduced in a self-consistent fashion with the help of a suitable application of linear response theory. Quantum effects in the fluctuations are governed by diffusion coefficients D_{μν}. The latter are obtained through a fluctuation dissipation theorem generalized to allow for a treatment of unstable modes. Numerical evaluations of the D_{μν} are presented. We discuss briefly how this picture may be used to describe global motion within a locally harmonic approximation.

nucl-th↗

arXiv1996

Fragments in Gaussian Wave-Packet Dynamics with and without correlations

Generalization of Gaussian trial wave functions in quantum molecular dynamics models is introduced, which allows for long-range correlations characteristic for composite nuclear fragments. We demonstrate a significant improvement in the description of light fragments with correlations. Utilizing either type of Gaussian wave functions, with or without correlations, however, we find that we cannot describe fragment formation in a dynamic situation. Composite fragments are only produced in simulations if they are present as clusters in the substructure of original nuclei. The difficulty is traced to the delocalization of wave functions during emission. Composite fragments are produced abundantly in the Gaussian molecular dynamics in the limit $\hbar \rightarrow 0$.

nucl-th↗

arXiv1996

Nuclear Shape Fluctuations in Fermi-Liquid Drop Model

Within the nuclear Fermi-liquid drop model, quantum and thermal fluctuations are considered by use of the Landau-Vlasov-Langevin equation. The spectral correlation function of the nuclear surface fluctuations is evaluated in a simple model of an incompressible and irrotational Fermi liquid. The dependence of the spectral correlation function on the dynamical Fermi-surface distortion is established. The temperature at which the eigenvibrations become overdamped is calculated. It is shown that, for realistic values of the relaxation time parameter and in the high temperature regime, there is a particular eigenmode of the Fermi liquid drop where the restoring force is exclusively due to the dynamical Fermi-surface distortion.

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