Electronic and phononic properties of V_2AlC via first principles

摘要

The electronic and phononic properties of V_2AlC have been extensively studied using ab initio pseudopotential density functional theory. Our investigations revealed that the longest V-V bond and its least variations have led to the stiffer c axis. The nearly unchanged net charge of the C atom under pressure has led to nearly unchanged overlapped populations along the C-V bond. The obvious charge transfer of V → Al has induced significant variations of the overlapped populations along Al-V and V-V bonds. An anomalous variation of charge transfer between V and Al atoms and V-V bond populations at about 700 GPa has been revealed, which may relate to its structural instability at about 731 GPa. Previously calculated structural instability at about 731 GPa has been successfully confirmed by the present phonon dispersion curve. The bonding natures are also studied by the electron density difference, electron density of states, and the energy band structure.