New approach to the positron distribution in metals and alloys

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Abstract
A positron pseudopotential is proposed that simplifies the description of a thermalized positron in a metal or alloy. The method is based on a factorization of the positron wave function into an energy-independent core function, which accounts for the detailed behavior of the positron when it approaches an ion core, and a smooth envelope or pseudo wave function. The pseudo wave function satisfies a Schrödinger-like equation with a relatively weak potential—the pseudopotential. Pseudopotential differences have been calculated for a number of alloys. The results indicate that the positron may have a strong preference or affinity for one sort of atom in binary alloys over the other. This relative positron affinity should lead to the positron preferentially annihilating with the electrons of that sort of atom in the alloy, and a method of detecting this from measured positron-annihilation data is proposed.