The maximal negative ion of molecules in Schr\"odinger, Hartree-Fock, and M\"uller theories

Abstract

Bounds are studied for the maximum number, $N_c$, of electrons that can be bound to $K$ atoms of the total nuclear charge $Z$. It is proved that $N_c < \min\{2Z+1, 1.22Z + 3Z^{1/3}\}$ in Schr\"odinger theory. This improves Lieb's bound $N_c < 2Z+K$ and extends Nam's results for an atom to the molecule. Moreover, the ionization conjectures for the molecules in Hartree-Fock and M\"uller theories are proved, i.e., $N_c \le Z + CKR_\mathrm{min}^{-3}$, where $R_\mathrm{min}$ is the minimal distance between atoms and $C$ is a universal constant.