Final Report: Travel Support Electromagnetic Induction Workshop, August 1, 1998 - July 31, 1999

During the tenure of this grant we focused our efforts on the treatment of (i) the behavior of the negative hydrogen ion, H{sup {minus}}, in a strong laser field (whose intensity extends well into the nonperturbative regime), and (ii) two-electron escape from a helium atom, He, by synchrotrons light. The calculations for H{sup {minus}} were done using perimetric coordinates u, v, and w, which are linear combinations of the three interparticle distances, together with the three Euler angles. The algebra involved in the implementation of the perimetric coordinate system can be quite formidable. However, we formulated [1] a general and tractable decomposition of the two-electron wavefunction which greatly facilitated the algebra. A complex Sturmian-type basis set, in these coordinates, was employed. One of the main advantages of the perimetric coordinates is that the matrices representing the system's Hamiltonian and its interaction with the radiation field are sparse, so that storage requirements and the number of operations are minimized. The correlation between the electrons is fully incorporated. Indeed, perimetric coordinates are ideally suited to situations where the correlation is strong; each of the planes u = 0, v = 0, ancl w = 0 has the special significance that the electrons lie on a line passing through the nucleus--on the same side, of the nucleus if u or v is zero, and on opposite sides if w = 0. We found [2] that the two-electron probability distribution for H{sup {minus}} has maxima on each of these planes