Theoretical Atomic Collisions

Yew-Kam Ho (L504)

The following projects are currently underway.

( I ) Studies of Atomic Resonance Phenomena

A method of complex-coordinate rotation is applied to investigate resonances in electron-atom scattering and in photo-absorption experiments of atoms and ions. The results will play an important role for investigating symmetries of atomic Hamiltonians, correlation effects of doubly excited electrons, and the underlying mechanism of autoionizations. Recent activities have focused on the following:

1. Calculating Feshbach and shape resonances in e^- - H scattering;
2. Investigating ¹P^o doubly excited states in He, with and without the presence of an external electric field. Our results are compared with experimental observations using synchrotron light sources around the globe;
3. Investigating the electric-field, magnetic-field, and the combined field effects on the Feshbach and shape resonances of H^- ; and
4. Calculating resonance states of many electron systems such as Be, Mg, and their iso-electronic sequences.

( II ) Interactions of positrons and positronium with atoms

Recent activities have focused on the following:

1. Calculating the ground and resonance state energies of positronium hydride (PsH);
2. Investigating the doubly-excited states of positronium negative ions; and
3. Studing of resonance phenomena in positron-hydrogen scattering and positronium-hydrogen scattering.

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