Mathematical Problems in Engineering
An upper and lower solution theory for boundary value problems modeled from the Thomas-Fermi equation, was presented. The approach was subjected to a boundary condition corresponding to the neutral atom with Bohr radius. The boundary conditions were investigated for the neutral atoms, the ionized atoms and the isolated neutral atoms.
Agarwal, R. P., & O'Regan, D. (2002). An upper and lower solution approach for a generalized thomas-fermi theory of neutral atoms. Mathematical Problems in Engineering, 8(2), 135-142. doi:10.1080/10241230212908