Ab initio study of the adsorption, diffusion, and intercalation of alkali metal atoms on the (0001) surface of the topological insulator Bi2Se3

We present the results of an \emph{ab initio} study of the adsorption, diffusion, and intercalation of alkali metal adatoms on the (0001) stepped surface of the topological insulator Bi$_2$Se$_3$ for the case of low coverage. The calculations of the activation energies of the adatoms diffusion on the surface and in the van der Waals gaps near the steps, as well as the estimation of diffusion lengths, show that efficient intercalation through the steps is possible only for Li and Na. Data obtained for K, Rb, and Cs atoms indicate that their thermal desorption at high temperatures can start before intercalation. These results are discussed in the context of the experimental data available \cite{1,2}. \begin{thebibliography}{99} \bibitem{1} Z.-H. Zhu, et al. Phys. Rev. Lett. {\bf 107}, 186405 (2011). \bibitem{2} M. Bianchi, et al. ACS Nano {\bf 6}, 7009 (2012). \end{thebibliography}