Positron trapping at vacancies was described on the basis of the optical theorem. The imaginary part of the optical potential was calculated, using an  ab initio  model, for the moment when electron-hole excitation took place. The analytical formulae for the optical potential were tested as a function of the positron incident energy, the positron binding energy, and the electron density parameter. The calculated optical potential range agreed well with the vacancy radius. The approach was used to describe the reported temperature dependence of the trapping rate at vacancies in pure metals. The resultant values of the optical potential were reasonable.

The Optical Potential Responsible for the Absorption of a Positron at a Vacancy J.Dryzek: Journal of Physics - Condensed Matter, 1997, 9[38], 8161-8