Competing local orders in liquid and amorphous structures of Ge ₂Sb₂Te₅: Influence of exchange-correlation functional

Liquid and amorphous structures of Ge₂Sb₂Te ₅ are theoretically studied with various exchange-correlation functionals. It is found that the balance of competing local orders around Ge atoms is substantially affected by the functional type, and the hybrid functional leads to structures that are in best agreement with experiment. The delocalization error inherent in semilocal functionals results in over-population of octahedral Ge configurations, which is compounded by the limitation of melt-quench processes in identifying the most stable amorphous structure. The present work underscores the importance of functional choice when competing local orders present in disordered systems.