Resonances close to the first ionization threshold of selenium

Relativistic multichannel theory has been used to calculate the even-parity Rydberg states and odd-parity autoionizing (AI) Rydberg spectrum converging to the limit of second and third excited core states of selenium (Se), taking into account the ionic core dipole polarization effect caused by the Rydberg electron. Six even-parity Rydberg series 4s(2)4p(3)(S-4(o))np(3)P(0,1,2) and 4s(2)4p(3)(S-4(o))np(5)P(1,2,3) are calculated, along with AI Rydberg states converging to 4s(2)4p(3)(D-2(3/2)o) or 4s(2)4p(3)(D-2(5/2)o) in J(pi) = (1)(-),(2)(-) or (3)(-) symmetry. In general, there is less than a 0.05 difference between calculated and experimental quantum defects. The influence of the perturbers on quantum defects and peak profiles has all been investigated. The accuracy of our calculations allows us to provide a reliable the assignment of the measured AI Rydberg states and the accompanying total angular momentum.