First-principles investigations of electronic and mechanical properties for stable Ge2Sb2Te5 with van der Waals corrections

The Te-Te weak van der Waals-type bonding plays an important role in Ge2Sb2Te5, a widely investigated phase-change material and a potential topological insulator. In this work, we have studied the electronic and mechanical properties of stable Ge2Sb2Te5 using ab initio calculations with the van der Waals corrections. The results show that the van der Waals corrections combined with hybrid functions improve the descriptions of the electronic structure of stable Ge2Sb2Te5. The band gap of ∼0.5 eV in very good agreement with the experimental value for stable Ge2Sb2Te5 has been successfully reproduced. Furthermore, we have predicted the elastic constants and mechanical properties of stable trigonal Ge2Sb2Te5.