Calculations of high Rydberg states for the lithium atom

Abstract

We present calculations of high Rydberg states for the lithium atom by two different theoretical methods. The first method is based on the $R$-matrix theory to obtain the energy levels and the quantum defects for the $1{s}^{2}nd\phantom{\rule{0.2em}{0ex}}^{2}D$ and $1{s}^{2}nf\phantom{\rule{0.2em}{0ex}}^{2}F$ states and their adjacent continuum states. Then the quantum defect functions of the two channels are obtained which vary smoothly with energy based on quantum defect theory. The second method is based on the full core plus correlation method. Our results are compared with data in the literatures; especially the results of the $R$-matrix method are in excellent agreement with microwave measurements for the lithium atom.