  Using first-principle plane wave method we investigate the effects of static
charging on structural, elastic, electronic and magnetic properties of
suspended, single layer graphene, graphane, fluorographene, BN and MoS2 in
honeycomb structures. The limitations of periodic boundary conditions in the
treatment of charged layers are clarified. Upon positive charging the band gaps
between the conduction and valence bands increase, but the single layer
materials become metallic owing to the Fermi level dipping below the maximum of
valence band. Moreover, their bond lengths increase and their in-plane
stiffness decreases. As a result, phonons are softened and frequencies of Raman
active modes are lowered. High level of charging leads to instability. We
showed that wide band gap BN and MoS2 slabs are metallized as a result of
electron removal and their outermost layers are exfoliated once the charging
exceeds a threshold value.
