Monitoring LaMnO3 Jahn-Teller distortion via electric-field gradient ab initio calculations

The electric field gradient (EFG) is studied via ab initio density functional theory calculations for the prototype LaMnO₃ manganite under ferromagnetic and A-type antiferromagnetic configurations with different values of on-site Hubbard U potential correction on the Mn-3d states. It is shown that the relaxation of internal atomic positions inhibits fully activated MnO₆ Jahn-Teller distortions, as determined by calculating the EFG tensor and the Jahn-Teller distortion parameter Δ. In fact, a strong correlation between the EFG values, especially at the La site, and the Jahn-Teller distortion was found and used to confirm the importance of an appropriate description of the electron-electron correlations when predicting the ground state properties of LaMnO₃ using a GGA + U approximation for the exchange-correlation functional.