Two-dimensional negative donors in magnetic fields

A finite-difference solution of the Schrödinger equation for negative donor centers D^- in two dimensions is presented. Our approach is of exact nature and allows us to resolve a discrepancy in the literature on the ground state of a negative donor. Detailed calculations of the energies for a number of states show that for field strengths less than γ=0.117a.u. the donor possesses one bound state, for 0.117<γ<1.68 a.u. there exist two bound states and for field strengths γ>~1.68 a.u. the system possesses three bound states. Further relevant characteristics of negative donors in magnetic fields are provided.