  In the present paper we analyze in detail several properties of the MgH$^-$
anion and the MgH neutral molecule using accurate ab initio quantum
computational methods in order to establish with higher reliability specific
molecular features like the gas-phase electron affinity (EA) , the Frank-Condon
(FC) factors for excitation of the neutral and of its anion to their lower
electronic states, and the general feasibility of employing the anion in
photodetachment experiments after its confinement in cold ion traps. The
calculations suggest that the EA value is in agreement with an existing early
experiment and further places on it a smaller error bar than that given before.
Accurate zero-point-energy (ZPE) corrections are also included in our
calculations and their effects discussed.
