  Herein a genetic algorithm for optimising the design of layered 2D
heterostructure is proposed. As a proof-of-concept it is applied to
Sb$_2$Te$_3$-GeTe phase-change material superlattices, and the resulting lowest
energy structure is grown experimentally. The similarity of the computational
and experimental structures is verified with the comparison of XRD spectra. The
structure is found to be within 0.92 meV/at. from the energetically most
favorable known structure for Ge$_2$Sb$_2$Te$_5$.
