| Quantum defects are determined for lithium, sodium, potassium, and beryllium by searching for the poles of the Schwinger T matrix along the negative real-energy axis. This method takes advantage of the fundamental ideas of QDT by using a Coulomb Green's function to factor out most of the energy dependence. For the alkali atoms, a single-channel calculation is performed using model potentials to include the effects of core polarization and correlation. Quantum defects accurate to 1% are easily obtained with small grids and small fixed basis sets for an entire Rydberg series up to principal quantum number, n, as high as 60. A multichannel extension of this method is used to determind neutral-beryllium quantum defects for the... |
