  We have performed collinear and non collinear calculations on neutral Bi4Mn,
and collinear ones on ionized Bi4Mn with charges +1 and -1 to find out why
theoretical calculations will not predict the magnetic state found in the
experiment. We have used the density functional theory to find a fit between
the theoretical prediction of the magnetic moment with the experimental value.
Our calculations have consisted in a structure search of local energy minima,
and then a search of the magnetic lowest energy state for each resulting
isomer. The geometry optimization found 3 local minima whose fundamental state
is the doublet spin state, which could not be found in previous theoretical
works, but they are higher in energy than the lowest-lying isomer by
approximately 1.75 eV. This magnetic state could help understand the
experiment. Calculations of non-collinear magnetic states for the Bi4Mn do not
lower the total magnetic moment. We conclude arguing how the 3 isomers with
doublet state could actually be the ones measured in the experiment.
