Positron annihilation in high-T/sub c/ superconductors

We report ab initio calculations of positron wave functions in the high-T/sub c/ superconductors YBa2Cu3O7, Bi2Sr2CaCu2O8, and Tl2Ba2CaCu2O8 using the general potential linearized augmented plane-wave method. The calculated positron wave functions are fairly insensitive to whether or not electron-positron correlation is included in the calculation for YBa2Cu3O7 and Tl2Ba2CaCu2O8, but the calculated positron density is quite sensitive to correlation in Bi2Sr2CaCu2O8. While the positron wave function samples primarily the chain region in YBa2Cu3O7, the results indicate that positrons should be good probes of the Cu-O layer-derived electronic states near the Fermi energy in Tl2Ba2CaCu2O8 since a large overlap with these states is predicted