Abstract
The crystal structures of the four experimentally observed phases of with space groups and are fully optimized by means of first-principles total-energy calculations. The relaxation of all internal parameters is achieved by using a simple finite difference method. For the structure without the mirror symmetry has a lower energy than the with mirror symmetry by 0.238 eV per formula unit. The calculated ground-state properties are found to be in good agreement with experimental values.
- Received 2 November 1999
DOI:https://doi.org/10.1103/PhysRevB.61.8696
©2000 American Physical Society