Assessment of several calculation methods for positron lifetime

抄録

We test seven different local density approximation (LDA) or generalized gradient approximation (GGA) forms of the enhancement factor and correlation potential for positron-lifetime calculations by using a useful database of experimental values based on the all-electrons approach: full-potential linearized augmented plane wave (FLAPW). To make a numerical assessment of these calculation methods, we use the mean-deviation and the reduced chi-squared as model selection criterions. We find that the tworecent LDA forms of the enhancement factor make distinct improvements upon the calculations for positron-lifetime compared with the older LDA form proposed by Arponen and Pajanne. However, all the LDA forms are still disfavored by the experimental data compared with the GGA forms. In addition, the two recent GGA forms do not yield any improvement when compared to experimental data over the original from given by Barbiellini et al., which is found to give the best agreement.