Duan Yiwu

Stabilizing Chaos in the rf-Driven Josephson Junction

The models of rf-driven Josephson junctions are investigated as the perturbed systems. It is shown that the heteroclinic orbits corrected by perturbations are stable if some relations between the initial constants and system parameters are satisfied, which leads to Melnikov chaos: To stabilize chaos one has to make the control parameters fitting the relations. The result is compared with the previous numerical work and a good agreement is found.

Exact Solution of a Many-Level Atom Interacting with a Monochromatic Field Without Rotating Wave Approximation*

In the coherent-state representation, the technique applied to the Jaynes-Cummings (JC) model in the absence of rotating wave approximation (RWA) is extended to the treatment of a many-level atom interacting with a monochromatic field. Some general results are presented.

A one-dimensional model of hydrogen molecular ion

We present a study on a one-dimensional hydrogen molecular ion under the Born-Oppenheimer approximation. A canonical transformation produces the classical system directly to be a pendulum. The quantum Schrodinger equation is solved analytically and the electronic energy curves show that the bound states of this 1D model differ from the 2D and 3D H-2(+). The vibration spectroscopy is also obtained by employing the Morses eigen wavefunctions as basis vectors to diagonalize the Hamiltonian for R. The semiclassical quantization yields electronic energies in agreement with the quantum ones reasonably.

Electron-electron correlation in the helium 3De doubly excited states

The qualitative features of the electron-electron correlation in the helium 3De doubly excited states have been investigated via an example of the N = 3, n=4 series. The angular, radial-angular and radial-radial correlations have been shown in detail and the anisotropism of the electronic cloud has been found. The features of the 3De states have been compared with those of the L ≤ 1 states.

One-body densities and features of the structure of the 2S+1Pe doubly excited helium states

The qualitative features of electron-electron correlation of the 2S+1Pe doubly excited helium states have been investigated. The anisotropism of the electronic cloud has been shown. A comparison has been made between the S=1 and S=0 states. The structures among the states, which belong to the same rotorlike supermultiplet, have also been compared with each other.

Modes of Internal Motion of Three-Body Systems Containing a Lighter Particle*

Since the internal motion of few-body systems appears as a variation of the shape, the shape-densities are extracted from the eigensolutions of the states of a 3-body system containing a lighter particle. Detailed analysis on the shape-densities is made and a certain modes of internal motion are discovered.