High precision calculation of the isotope shift of the $3{}^{2}S_{1/2}\mathrm{\text{−}}2{}^{2}S_{1/2}$ transition in lithium is presented. The wave function and matrix elements of relativistic operators are obtained by using recursion relations. Apart from the relativistic contribution, we obtain the nuclear polarizability correction for ${}^{11}\mathrm{Li}$. The resulting difference of the squared charge radii ${}^{11}\mathrm{Li}\mathrm{\text{−}}{}^7\mathrm{Li}$ based on the measurements of Sánchez et al. [Phys. Rev. Lett. 96, 033002 (2006)] is $\delta r_{\mathrm{ch}}^2=0.157(81){\mathrm{fm}}^2$, which significantly differs from the previous evaluation.

• Received 29 July 2006

DOI:https://doi.org/10.1103/PhysRevLett.97.133001