Electric-field gradient at oxygen sites in RBCO: Effects from a positive muon

A limited quantum chemistry approach has been used to examine changes to the electric-field gradient at oxygen sites in rare-earth barium copper oxides (RBCO) due to a bonded muon (or hydrogen). Results are reported for an all electron, extended basis set calculation for an OMu^– molecule which is embedded in various point charge clusters to simulate the RBCO crystal environment. Differences between the gradients for O^2– and OMu^– are examined for five likely muon bond sites. In each case the muon significantly modifies the calculated gradient.This work was supported by the Robert A. Welch Foundation (Grant D-1053). We also wish to thank Carel Boekema for numerous discussions during the course of this project.