TABLE V: Individual contributions to the specific differenc e Δ $^{′}$E of the hyperfine splittings for bismuth $^{209}$Bi. The units are meV. Δ E (2 s ) ξ Δ E (1 s ) Δ $^{′}$E Dirac value 844.829 876.638 − 31.809 Interelectronic interaction, ∼ 1 /Z − 29.995 − 29.995 Interelectronic interaction, ∼ 1 /Z 2 and h.o. 0.25(4) 0.25(4) QED − 5.052 − 5.088 0.036 Screened SE 0.381 0.381 Screened VP − 0.187(6) − 0.187(6) Total − 61.32(4) 29