Abstract:
The Structural and electronic Properties of Iron(ii)Oxides (F eO) is investigated with
density functional theory (DFT) using Quantum Espresso package. Our study is
based on Density Functional Theory (DFT) with the Perdew-Burke-Ernzerhof (PBE)
exchange-correlation functional, Vanderbilt (ultra soft) pseudo potentials and the
plane wave basis set implemented in the Quantum-ESPRESSO package. The calcu lation of the total minimum energy and the total minimum force of F eO is calculated
as a function of cutoff energy and K-points sampling. The total minimum energy
per cell is monotonically decreasing with increasing cutoff energy due to variational
principle. However, this trend can not be predicted from increasing the k-points sam pling. Moreover, the equilibrium lattice constant is calculated using results obtained
from energy convergence test (i.e., 70 Ry and 6 × 6 × 6 ). The computational value
of the equilibrium lattice constant is 7.5˚A. This result is underestimated by 8% from
the experimental value is 8.19˚A. In addition to this the band structure and total
density of state are calculated. From the band structure it is observed that the band
gap value is under estimated as compared to the experimental band gap value. This
descripancey is due to the inability of GGA to approximate the exchange correlation
potential of d and f block elements. The discontinuety of density of state at Fermi
level show that FeO is a semiconductor.
