ACCURATE CALCULATIONS FOR THE EVEN-PARITY CORE-EXCITED P-2 STATES OF NEUTRAL LI

Nonrelativistic configuration-interaction calculations have been carried out with orbital basis specifically adapted for each one of the first seven even-parity P2 bound states of neutral Li. The results show that the lowest four P2 states have recently been observed by absorption spectroscopy from the 1s22p state. The calculated transition wavelengths (20.7452, 19.7613, 19.4728, and 19.4065±0.0005 nm agree well with the experimental ones (20.744, 19.762, 19.474, and 19.405±0.002 nm). Electric dipole transition probabilities to the 1s22p, 3p and 4p states have also been calculated. The configurations for the two lowest P2(1) and P2(2) states are 1s2p2 and (1s2p)P33p, respectively. The (1s2p)P3 np and (1s2p)P1 n′p series almost coincide at n=4, n′=3, and as a consequence, the P2(3) and P2(4) levels are approximately described by (1s2p)P34p±(1s2p)P13p. This is the simplest known example of two-level series which mutually perturb each other. © 1979 The American Physical Society.