Do oxygen vacancies trap positions in the superconducting cuprates YBa2Cu3O7and YBa2Cu3O6?

Abstract
The authors have calculated the band structure for positrons in the high-temperature superconductors YBa2Cu3O7 and YBa2Cu3O6 using the LMTO ASA method. On the basis of the results they argue that it is very unlikely that oxygen vacancies will trap positrons in these compounds.