Francesco Petruccione

Non-Markovian dynamics in a spin star system: Exact solution and approximation techniques

The reduced dynamics of a central spin coupled to a bath of

A numerical stochastic approach to network theories of polymeric fluids

N

Continuous time simulation of transient polymer network models

spin-

Consistently averaged hydrodynamic interaction for dumbbell models in elongational flow

\frac{1}{2}

Concepts and Methods in the Theory of Open Quantum Systems

particles arranged in a spin star configuration is investigated. The exact time evolution of the reduced density operator is derived, and an analytical solution is obtained in the limit

Simulation of one-dimensional noisy Hamiltonian systems and their application to particle storage rings

N\ensuremath{\rightarrow}\ensuremath{\infty}

A New Model for Polymer Melts and Concentrated Solutions

of an infinite number of bath spins, where the model shows complete relaxation and partial decoherence. It is demonstrated that the dynamics of the central spin cannot be treated within the Born-Markov approximation. The Nakajima-Zwanzig and the time-convolutionless projection operator technique are applied to the spin star system. The performance of the corresponding perturbation expansions of the non-Markovian equations of motion is examined through a comparison with the exact solution.

Continuous time simulation of the Doi-Edwards model

A new numerical approach is presented to exactly solve the convection equation arising in network theories. The method is based on a direct stochastic interpretation of the convection equation. We show that with this approach models can be studied extensively which are not solvable analytically. It turns out that a conceptually simple approach to network theories predicts a qualitatively satisfying rheological behavior.

Nonlinear dumbbell model for flexible polymers: dynamical phenomena

A continuous time simulation algorithm for polymer melts is presented. The method is introduced via an explicit application to transient polymer network models, but it may be applied to a much larger class of models. The central quantity of the simulation is the lifetime of a strand. This can be calculated according to a proper distribution, which may depend on the orientation and length of the generated new strand. As the equation of motion of the strand can be integrated analytically during the lifetime of the strand, the procedure works much more efficiently than a previous simulation algorithm for transient network models. The material functions can be calculated as ensemble averages. The new method is shown to work for time‐dependent flows. A simplified algorithm for steady flows is also given. Some predictions are made for a specific configuration‐dependent transient network model.

On a Liouville-master equation formulation of open quantum systems

We apply the recently proposed consistent averaging approximation for the hydrodynamic interaction to elongational flow. This flow situation can be treated to a great extent analytically for Rouse and FENE‐P dumbbells. In both cases expansions for the elongational viscosity are presented for low and high elongational rates.