Cusp conditions and convergences in Close-Coupling wavefunctions, for inner-shell electrons

D.M. MITNIK AND J.E. MIRAGLIA

Buenos Aires, Argentina

Conferencia; Thirteenth International Symposioum on Polarization and Correlation in electronic and Atomic Collision; 2005

ICPEAC

We have developed an exact numerical method for calculating the full spectrum of the Helium atom in a box [Mitnik, 2002, Mitnik 2004]. The method provides a complete non-perturbative close-coupling calculation, and consists on the direct diagonalization of the two-electron Hamiltonian in a numerical grid. On the other hand, we have introduced simple variational wave functions to describe the K-shell orbital electrons of neutral atoms subject to the same influence of the upper shells. These functions are strongly correlated and satisfy the Kato cusp conditions. We have compared the spherical harmonics expansion of these functions with the one obtained with nonperturbative, fully quantal close-coupling (CC) calculation of the exact wave functions of K-shell electrons in a numerical lattice. It provides a good test to the convergence of the partial waves expansion in the CC calculation. Since our variational functions have all the cusp conditions, it is useful to know how many partial waves are needed to satisfy these conditions.