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The effect of positron-phonon scattering on positron trapping at defects in metals: formalism and low-order theory

1977; IOP Publishing; Volume: 7; Issue: 10 Linguagem: Inglês

10.1088/0305-4608/7/10/008

1747-3918

T. McMullen,

Graphene research and applications

A fully quantum mechanical theory is developed. The theory is applicable to strong as well as to weak trapping, and includes the effect of trapping on the positron distribution in the vicinity of the trap. Nonequilibrium many-body theory is used to formulate the problem in order to include positron annihilation in a natural way. It is concluded that for weak trapping the golden rule is applicable if an initial distribution of thermalised positrons including the positron-phonon interaction is used. For stronger trapping the lowest-order correction to the golden rule is calculated and the corresponding positron density is examined. The positron density around the trap is altered by the trapping process as time progresses, and this is illustrated by calculations of the time evolution of the positron density near a monovacancy.