Ab initio study of the (2 × 2) phase of barium on grapheneCesare Tresca, Nikolay I. Verbitskiy, Alexander Grüneis and Gianni ProfetaEur. Phys. J. B, 91 7 (2018) 165DOI: https://doi.org/10.1140/epjb/e2018-90141-6