## Stable He$^-$ can exist in a strong magnetic field    [PDF]

A. V. Turbiner, J. C. Lopez Vieyra
The existence of bound states of the system $(\al,e,e,e)$ in a magnetic field $B$ is studied using the variational method. It is shown that for $B \gtrsim 0.13\,{\rm a.u.}$ the system $(\al,e,e,e)$ gets bound with total energy below one of the $(\al,e,e)$ system. It manifests the existence of the stable He$^-$ atomic ion. Its ground state is spin-doublet $^2(-1)^{+}$ at $0.74\, {\rm a.u.} \gtrsim B \gtrsim 0.13\, {\rm a.u.}$ and then becomes spin-quartet $^4(-3)^{+}$ for larger magnetic fields. For $0.8\, {\rm a.u.} \gtrsim B \gtrsim 0.7\, {\rm a.u.}$ the He$^-$ ion has two (stable) bound states $^2(-1)^{+}$ and $^4(-3)^{+}$.
View original: http://arxiv.org/abs/1307.4810