Positron lifetime calculation of defect in palladium containing hydrogen and helium

Lattice defects containing hydrogen and helium in Pd have been studied by positron model calculations using Density Functional Theory [DFT] in its local density approximation [LDA] [1] implementation. A correlation between the positron lifetime, positron ground stage energy and number atoms of H and He has been established. It was found that the value of positron lifetime for perfect Pd lattice is 106 ps and for mono vacancy is 184 ps which corresponds to the experimental values.