Potential renormalization by tunneling induced intrinsic transition
  The screening effects by bound target electrons in low energy nuclear reactions in laboratory experiments can be well represented in terms of a constant shift of the tunneling potential barrier as postulated in all previous analyses if the electronic cloud were static or structureless and lied outside the tunneling region. In this paper, using a semiclassical mean field analysis of a simple two-level coupled-channels problem, we suggest that there could occur a strong quantum transition of electrons from excited to the ground states in the tunneling region, leading to a spatially dependent screening potential. We thus show the necessity of the dynamical treatment of the tunneling region in order to properly assess the screening effects by bound target electrons in low energy nuclear reactions in laboratories. 
Noboru Takigawa, Sachie Kimura and David M. Brink