%0 Journal Article
%T Supercritical instability in graphene with two charged impurities
%A E. V. Gorbar
%A V. P. Gusynin
%A O. O. Sobol
%J Physics
%D 2013
%I arXiv
%R 10.1103/PhysRevB.88.205116
%X We study the supercritical instability in gapped graphene with two charged impurities separated by distance R using the two-dimensional Dirac equation for electron quasiparticles. Attention is paid to a situation when charges of impurities are subcritical, whereas their total charge exceeds a critical one. The critical distance R_{cr} in the system of two charged centers is defined as that at which the electron bound state with the lowest energy reaches the boundary of the lower continuum. A variational calculation of the critical distance R_{cr} separating the supercritical (R<R_{cr}) and subcritical (R>R_{cr}) regimes is carried out. It is shown that the critical distance R_{cr} increases as the quasiparticle gap decreases. The energy and width of a quasistationary state as functions of the distance between two impurities are derived in the quasiclassical approximation.
%U http://arxiv.org/abs/1307.7728v2