It was shown with the help of first-principles calculations that the occurrence of stacking faults changed the density of nickel. Calculations based upon a twelve {111}-plane super-cell of face-centered-cubic nickel showed that the stacking-fault energy in the case of so-called conventional stacking was higher by about 2mJ/m2 than that of a super-cell having an appropriate dilation along the fault-plane normal. The {111}-type stacking-fault energy of fcc-Ni, 136.683mJ/m2, was calculated using a 4.09746 x 105/mm stacking-fault density. This resulted in a decrease in the bulk density of fcc-Ni of 0.0895%. The approach of relaxing a structure with stacking faults along the plane normal could be extended to the calculation of more accurate generalized stacking faults and to the measurement of lattice distortion due to various values of defect density.

Contribution of Stacking Fault in Lowering the Theoretical Density of Nickel. J.Mittra, U.V.Waghmare, A.Arya, G.K.Dey: Computational Materials Science, 2014, 81, 249-52