Abstract
The full zone-center optical phonon spectrum and the exchange coupling constant of the uniform collinear antiferromagnetic (AFM) ordered phase of are calculated within density functional theory using the local spin density approximation (LSDA), the LSDA plus Hubbard , and the spin-polarized generalized gradient approximation . The AFM ordering is found to induce splittings in the infrared-active phonon modes, confirming the importance of spin-phonon coupling in . The and the give magnitudes of phonon frequencies close to experiment, while the LSDA frequencies are slightly softer. However, only the exchange constant and phonon splittings are consistent with experiment and previous calculations. A correspondence between the exchange constant and the splittings for the infrared-active phonon modes is found.
- Received 8 November 2006
DOI:https://doi.org/10.1103/PhysRevB.75.054304
©2007 American Physical Society