Investigation of the structure and properties of rhombohedral Cu-Ge-Te alloys by ab initio calculations

► Structure and properties of CunGe32-m-nTe32 were studied by ab initio calculations. ► Formation energies of CunGe32-m-nTe32 were calculated according to synthesis routes. ► It is energetically most favorable to dope Cu in defective Ge32-mTe32. ► Cu has slight effect on the structure property and chemical bonding of Ge32-mTe32. ► Cu may decrease (increase) the electrical resistivity of Ge32-mTe32 (ideal GeTe).