X α ‐DVM modelling of oxygen transport in YBa 2 Cu 3 O 7‐δ and SrFeO 3

The reasons for oxygen transport in YBa 2 Cu 3 O 7‐δ and SrFeO 3 were investigated, using the X α ‐discrete variation method. Reduced binding energy and other parameters of the electronic energy structure were calculated for a number of crystal fragments within the T and O phases of YBa 2 Cu 3 O 7‐δ and the cubic phase of SrFeO 3 . The following results were obtained: (i) test calculations of reduced binding energy confirmed that high temperature should be a condition of existence of the T phase, as compared with the O phase of YBa 2 Cu 3 O 7‐δ ; (ii) an increase in temperature up to ∼400°C points to the beginning of the Jahn–Teller dynamic effect in SrFeO 3 ; and (iii) transport of neutral and charged oxygen atoms results in distributions of stable and unstable oxygen vacancies, respectively. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006