Abstract
The energy landscape of under pressure is explored by ab initio evolutionary calculations. Two new tetragonal structures, with space groups and , are predicted to be lower in enthalpy by 15.4 and , respectively, than the earlier proposed phase. We have simulated x-ray diffraction spectra, lattice dynamics, and equations of state of these phases. The density, volume contraction, bulk modulus, and simulated x-ray diffraction patterns of and structures are in excellent agreement with the experimental results.
- Received 2 October 2012
DOI:https://doi.org/10.1103/PhysRevLett.109.245503
© 2012 American Physical Society