The term "topotaxy" describes crystal growth process based on recrystallization in which the crystallographic orientation of the parent crystal determines that of the product composed crystal. Recently, a new method was developed and reported in the journal "Nature Nanotechnology" that converts InAs wurtzite nanowires into Eu₃In₂As₄. The mechanism of topotactic exchange rebuilding the structure of nanowires was discovered at the Weizmann Institute of Science in Israel in cooperation with IF PAN and other centers.The method is based on spontaneous atom exchange between the supplied gas and the nanowire, while simultaneously rebuilding the crystal structure. Our molecular dynamics simulations confirm the existence of this mechanism. This conversion involves the evaporation of europium and arsenic onto the nanowires in a controlled environment. Europium replaces indium in the nanowire shell, resulting in the formation of a new Eu₃In₂As₄ shell that gradually surrounds the original InAs core. Calculations indicate that Eu₃In₂As₄ acts as an "axion insulator", a unique type of material characterized by special surface states that could have significant applications in magnetically controlled electronics. The vapour-solid topotactic exchange that rebuilds the nanowire structure could open new avenues for studying complex magnetic and topological states in this and other exotic materials. This method has the potential to expand the range of possible materials that form nanowires.