In framework of a variational method the molecular ion $H_2^+$ in a magnetic field is studied. An optimal form of the vector potential corresponding to a given magnetic field (gauge fixing) is chosen variationally. It is shown that for any magnetic field strength as well as for any orientation of the molecular axis the system $(ppe)$ possesses a minimum in the potential energy. The stable configuration always corresponds to elongation along the magnetic line. However, for magnetic fields $B \gtrsim 5\times 10^{ 11} G$ and some orientations the ion $H_2^+$ becomes unstable decaying to $H{ -atom} + p$.
Categories: astro-ph
