First-principles calculation of positron annihilation characteristics in solids: From positron to positronium

Two schemes to perform first-principles calculations of positron annihilation characteristics in solids are outlined. The schemes are based on two-component density functional theory and use pseudopotential plane waves and full potential linearized augmented plane waves, respectively. To demonstrate the agreement between theory and experiment, a case study of positron annihilation in fcc and bcc Cu is presented and the calculated positron lifetime, two-dimensional angular correlation of annihilation radiation (2D-ACAR) distribution, and coincidence Doppler broadening (CDB) are compared with our experiments. It is also described that the positronium. in solids can be modeled from the first principles starting from the positronic and electronic structures of the density functional theory.