THEORETICAL DETERMINATION OF ENERGIES AND WIDTHS OF AUTOIONIZING STATES OF THE BE ATOM

The energy and width of the 2p(2) S-1 autoionizing state of the Be ato m were calculated. A series of multireference configuration-interactio n (MRCI) calculations with an extensive Slater-type function (STF) bas is set was carried out and the full CI energy was estimated for each o f the neutral and ionized states. The estimated energy of 2p(2 1)S is 1126 cm(-1) with respect to the 2s S-2 ionized state. The photoionizat ion cross section from the 2s2p (1p0) state was calculated by using th e R-matrix method. The resultant energy and width are 1092 cm(-1) and 106 cm(-1) respectively, in reasonable agreement with the observed val ues of 997 +/- cm(-1) and 74.9 cm(-1). The energies and widths of the 2pnp S-1 series up to n = 11 were also calculated.