A silicon impurity in BCC iron: ab initio simulation of properties and energy parameters

The ab initial modeling of the equilibrium structure and properties of silicon atoms in BCC iron is performed in WIEN2k software package. We have investigated iron employing the full potential linear augmented plane-wave LAPW method within the generalized gradient approximation PBE-GGA, in the supercell of 54 iron atoms with periodic boundary conditions. This is the most powerful technique in the framework of Density Functional Theory. The optimal values of the basic simulation parameters of silicon impurities in the BCC iron are determined. They allow calculating the energy performance of the system with an accuracy of not less than 0.01 eV. The calculation of energy of dissolution of silicon atoms in the ferromagnetic phase of BCC iron is conducted using the obtained simulation parameters. It amounts to -1.19 eV. Silicon atoms experience a strong mutual repulsion in the first two coordination spheres, which is further decreasing. After the third coordination sphere, the repulsion of the atoms becomes close to zero. During dissolution, silicon does not change the BCC lattice parameter and does not affect the iron lattice. The magnetic moment of iron atoms in the first environment decreases from 2.23 μB to 2.045 μB. Dissolution of 1.85 at. % of silicon leads to a decrease in the average magnetic moment per iron atom by 0.02 μB and a decrease in the bulk modulus of compression.