Electronic and optical properties under pressure effect of alkali metal oxides M. Moakafi, R. Khenata, A. Bouhemadou, H. Khachai, B. Amrani, D. Rached and M. Rérat Eur. Phys. J. B, 64 1 (2008) 35-42 Published online: 16 July 2008 DOI: 10.1140/epjb/e2008-00286-6