SelfDiffusion Coefficient of fcc Mg FirstPrinci

Authors: Dongdong Zhao Yi Kong Aijun Wang Liangcai Zhou Senlin Cui Xiaoming Yuan Lijun Zhang Yong Du

Publish Date: 2011/02/23

Volume: 32, Issue: 2, Pages: 128-137

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Abstract

Firstprinciples calculations and semiempirical equations are employed to determine the selfdiffusion mobility of fcc Mg All factors entering the vacancymediated selfdiffusion coefficient which include the equilibrium lattice parameter the enthalpy of vacancy formation and atom migration and the vibrational entropy of vacancy formation as well as the effective frequency are evaluated with the local density approximation LDA and generalized gradient approximation GGA in firstprinciples calculations These computed quantities are then utilized to calculate the selfdiffusion coefficient of fcc Mg For comparison four widely used semiempirical equations are also used to estimate the selfdiffusion coefficient of fcc Mg The comparisons show that firstprinciples calculations and semiempirical equations yield values close to the activation energy Q for selfdiffusion of fcc Mg from the LDA calculation but the diffusion prefactor D 0 predicted from the four semiempirical equations are all about one order of magnitude larger than those from the firstprinciples calculations Based on the comparison for the selfdiffusion coefficients of fcc Al computed with the firstprinciples method and semiempirical approaches it is concluded that the selfdiffusion coefficient of fcc Mg calculated with the LDA method is more accurate than the estimation from semiempirical approaches

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