  We give a basic explanation for the oscillating properties of some physical
quantities of a two-electron quantum dot in the presence of a static magnetic
field. This behaviour was discussed in a previous work of ours [AM Maniero,
{\it et al}. J. Phys. B: At. Mol. Opt. Phys. 53:185001, 2020] and was
identified as a manifestation of the {\it de Haas-van Alphen} effect,
originally observed in the framework of diamagnetism of metals in the 30's. We
show that this behaviour is a consequence of different eigenstates of the
system assuming, in a certain interval of the magnetic field, the condition of
the lowest energy singlet and triplet states.
