Self-diffusion coefficient of fe, pb, ni and Cr by molecular dynamics simulation using the potential morse

Abstract

The molecular dynamics simulation using the Morse potential has been applied to calculate the value of self-diffusion coefficients D ( T ) of some pure metals as Pb, Cr, Ni, and Fe. The simulation then was done using the MOLDY molecular dynamics program. The procedure to calculate these coefficients following several steps: first, determining the Morse potential parameters as D , a and r 0 ; second, simulating the material under consideration using Moldy based on the appropriate ensemble; third, diffusion coefficient calculation using the Green-Kubo method for specific temperature; and fourth, the temperature-dependent diffusion coefficient D ( T ) based on the Arrhenius. The simulation work has obtained the best results as following: for Pb metal the Morse potential parameter ( a = 1.4795 A −1 , r 0 = 3.733 Å, and D = 0.2348 eV ) with D ( T ) = 9.68 × 10 − 9 exp ( − 3890.79 R T ) [ m 2 / s ] ; for Cr metal the potential parameters ( D = 0.3292 eV , a = 1.1005 A −1 , and r 0 = 2.2032 Å), with D ( T ) = 1.73 × 10 − 3 exp ( − 8725.54 R T ) [ m 2 / s ] ; for Ni metal the Morse potential parameter ( D = 0.3784 eV , a = 1.0649 A −1 , r 0 = 2.085 Å), with D ( T ) = 8.5 × 10 − 4 exp ( − 15794.9 R T ) [ m 2 / s ] ; and for Fe metal the potential parameter ( D = 0.4174 eV , a = 1.5974 A −1 , r 0 = 2.840 Å) with D ( T ) = 4.22 × 10 − 7 exp ( − 5878.49 R T ) [ m 2 / s ] . The calculated diffusion coefficients of the work have significant application as for the corrosion study of steels in nuclear reactor design.