Calculation of Zn-doped y ceramics by the electron-correlated embedded-cluster method

An approach, where the embedded-cluster method (ECM) is applied in the fram e of the Gaussian program to calculate the local electronic structure of cr ystals at the electron correlation level is presented. This approach is app lied to a ground-state electronic structure calculation of the pure and Zn- doped Y123 ceramics at the second-order Moller-Plesset (MP2) correlation le vel (the ECM-MP2 approach). This allows to study the influence of the Zn do ping on the charge distribution and the hole symmetry on the Cu and O ions obtained in the natural bond orbital (NBO) population analysis at the MP2 l evel. The possible mechanisms of the degradation of superconductivity in th e Zn-doped Y ceramics are discussed. (C) 2000 John Wiley & Sons, Inc.