Further desodiation now leads to the so-called Prussian Yellow (Fe[Fe(CN) 6 ]) and the removal of one of the electrons out of the t 2g states of the low spin Fe. This does obviously not erase the benefits of the t 2g /e g splitting. If anything, it actually gives rise to a small energy benefit by the formation of the a 1g /e g states. This energy gain would suggest a small driving force towards a rhombohedral crystal system, which is not known from the experiment. Therefore, we shall seek to explore reasons as to why the rhombohedral structure is observed for Prussian White only from the standpoint of atomistic first-principles calculations.