First-principles investigation of the cooperative Jahn-Teller effect for octahedrally coordinated transition-metal ions
Fundamental aspects of the cooperative Jahn-Teller effect are investigated using density functional theory in the generalized gradient approximation. LiNiO{sub 2}, LiMnO{sub 2}, and LiCuO{sub 2} are chosen as candidate materials as they possess small, intermediate, and large cooperative Jahn-Teller distortions, respectively. The cooperative distortion is decomposed into the symmetrized-strain modes and k=0 optical phonons, revealing that only the E{sub g} and A{sub 1g} strain modes and E{sub g} and A{sub 1g} k=0 optical-phonon modes participate in the cooperative distortion. The first-principles results are then used to find values for the cooperative Jahn-Teller stabilization energy and the electron-strain and electron-phonon coupling. It is found that the dominant source of anisotropy arises from the third-order elastic contributions, rather than second-order vibronic contributions. Additionally, the importance of higher-order elastic coupling between the E{sub g} and A{sub 1g} modes is identified, which effectively causes expansion of A{sub 1g}-type modes and allows for a larger E{sub g} distortion. Finally, the strain anisotropy induced by the antiferromagnetically ordered states is shown to cause a significant difference in the cooperative Jahn-Teller stabilization energy for the different orientations of the cooperative distortion.
- Sponsoring Organization:
- (US)
- OSTI ID:
- 40203496
- Journal Information:
- Physical Review B, Vol. 63, Issue 22; Other Information: DOI: 10.1103/PhysRevB.63.224304; Othernumber: PRBMDO000063000022224304000001; 006122PRB; PBD: 1 Jun 2001; ISSN 0163-1829
- Publisher:
- The American Physical Society
- Country of Publication:
- United States
- Language:
- English
Similar Records
Simulating Charge, Spin, and Orbital Ordering: Application to Jahn–Teller Distortions in Layered Transition-Metal Oxides
Origins versus fingerprints of the Jahn-Teller effect in -electron perovskites