d “Electronic and structural properties of Iron using density functional theory (QUANTUM ESPRESSO

Abstract

The electronic and structural properties of Iron (Fe) were investigated using density functional theory (QUANTUM ESPRESSO). Iron is the main ingredient used to make steel and the crystalline structure is body center cubic (BCC) at 300 kelvin. The unknown exchange correlation energy was computed by model of local density approximation (LDA) and generalized gradient approximation (GGA). The total minimum energy of Iron is calculated as function cutoff energy and k.point grid. The convergence of total energy is tested and achieved at the energy cutoff 60 Ry for the first case and at 16×16×16 k.point grid size for the second case. The total magnetization and the total stress of Iron is performed as function of degauss. The result shows that total magnetization of Fe per atom is 1.99 Bohr Mag/cell and the total stress Fe per atom is -26.50 Ry/Bohr3 . In addition to this, equilibrium lattice constant is calculated with lattice constant between 4.80 Bohr and 5.55 Bohr. The computational value of the equilibrium lattice is 5.10 Bohr and this result is best agreement when we compare the equilibrium lattice constant with experimental value of 5.217 Bohr. Finally, the four different smearing schemes:- Marzari-Vanderbilt, Methfessel-Paxton, Gaussian and Fermi-Dirac are tested for convergence of the total minimum energy. The result shows that minimum energy converges very fast for Marzari-Vanderbilt, Methfessel-Paxton.