Calculation of Rydberg energy levels for the francium atom

Based on the weakest bound electron potential modeltheory, the Rydberg energy levels and quantum defects ofthe $n$p$^{2}$P$^{rm circ}_{1 / 2}$ ($n$=7--50) and$n$p$^{2}$P$^{rm circ}_{3 / 2}$ ($n$=7--50) spectrum series forthe francium atom are calculated. The calculated results are inexcellent agreement with the 48 measured levels, and 40 energylevels for highly excited states are predicted.