A. N. Sil

Variational calculation for the doubly excited state (2p2)3Pe of BeIII

Nonrelativistic energy of the (2p(2))(3)P(e) state of Be(2+) has been calculated using Ritz-variational method. The trial wave function is of Hylleraas type. The upper-bound energy E=-3.382 712 420 77 a.u. calculated by us is the lowest yet obtained.

Exotic affinities under Debye plasma

Muonic affinities of the exotic system π+μ− have been calculated variationally using a general three-body formalism. The system is found to be stable in the ground state under Coulomb coupling. The stability of this system under an external plasma environment has been analyzed using multiterm correlated basis sets of Hylleraas type. The effect of external plasma has been incorporated using the standard Debye screening model. The system tends toward gradual instability under the increased strength of the plasma, and the affinities have been found to decrease gradually and systematically. The effect of correlation on the exotic affinities has been analyzed in detail. The effect of angular correlation on exotic affinities is found to be around 40–80%.

One photon two electron excitations between doubly excited states of helium.

Variational calculations using Hylleraas coordinates have been performed for the first time for estimating the energies of 3dnf((1,3)D(o)) state of helium for n=4,5,6. We predict absorption peaks at 12.219, 12.647, and 12.857 eV for the (3)D(o) series converging to N=3 ionization threshold of He(+) which can be expected to be observed in the experiment of single photon double excitation of lowest (3)P(e) state of helium placed in synchrotron radiation.