Electronic and structural properties of aluminum with respect to density functional theory

Abstract

In this study the electronic and structural properties of Aluminum (Al) were investigated with respect to density functional theory by using Quantum Espresso Package.The local density approximation (LDA) and the generalized gradient approximation (GGA) were used to compute the exchange correlation energy.The total minimum energy of Aluminum is performed as a function of cutoff energy and Monk horst- pack grid size .The results show that, the total minimum energy per atom is monotonically decreasing with increasing cutoff energy due to variational principle.However,there is no systematic trend can be predicted from just increasing the k.point sampling .The total minimum force on Al is computed by displacing Al atom as a function of cutoff energy and k.point grid size by 0.05 Bohr. Moreover, the total minimum force is converged at the cutoff 60 Rydberg and Monk horst-pack mesh of 9 × 9 × 1 k.point.In Addition to this, the equilibrium lattice constant is calculated with different lattice constant.The computational value of the equilibrium lattice is 7.4 Bohr.This result is in good agreement with experimental value. Finally, the four different smearing schemes: Marzari-Vanderbilt, Methfessel -Paxton, Gaussian and Fermi-Dirac are checked for convergence issues of the total minimum energy.The results show that the total minimum energy converges very slowly for Gaussian (Ga) and Fermi-Dirac smearing.