POSITRON BINDING - A POSITRON-DENSITY VIEWPOINT

The binding of a single positron to a many-electron system (in the fie ld of a fixed nuclear configuration) is viewed in terms of positron an d electron densities. Following the treatments due to Levy and co-work ers [Phys. Rev. A 32, 2010 (1985); 30, 2745 (1984)], certain general i ntegral conditions and also an exact differential equation for the pos itron density are derived. It is demonstrated further that within a de nsity-functional approach, decent estimates to the positron affinity f or negative ions can be obtained by invoking the Slater transition sta te concept. Finally, the redistribution in the electron part brought a bout by transiently binding the positron to the negative ion is discus sed at the density-matrix level.