Structural And Electronic Properties Of Trisodium Antimonide With And With Out Considering Spin Orbit Coupling

Abstract

Trisodium antimonide (Na3Sb) is a narrow band gap material and it is a binary compound crystallize in a hexagonal structure with the space group P 63/mmc. Since Na3Sb is the system with many electron it is a bit challenging and complicated to solve analytically. To solve this many electron system, the density functional theory is preferred as an accurate and reliable tool. The first principle calculation based on density functional theory (DFT) was used to investigate the structural and electronic properties of Na3Sb using Quantum Espresso package. A number of convergence test were performed to establish the optimal value of various parameter in the numerical calculations. Firstly, the total minimum energy of Na3Sb per cell was calculated of as a function of cutoff energy and k-point sampling. Secondly, the optimal lattice constant of Na3Sb was calculated for a series of possible parameters using the result obtained energy convergence test 30Ry and 6x6x6 k-points. Moreover the band structure of Na3Sb with and with out SOC and total and partial density of state of Na3Sb have been calculated based on the frame work of density functional theory. The results of the calculation shows that the total minimum energy of Na3Sb per cell is monotonically decreasing with increasing cutoff energy. But,this trend can not be predicted from increasing the k-point sampling. In the calculation of lattice constant the equilibrium point described in two way, the firs equilirium point achieved with fixed experimental value of lattice constant a = 10.119483Bohr at lattice constant c = 1.8Bohr, the calculated error value is 1.5058 ,