Simultaneous softening of Cu{sub 3}N phonon modes along the T{sub 2} line under pressure: A first-principles calculation
- Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100080 (China)
Cu{sub 3}N band structures and phonon dispersion curves under pressure are calculated using first-principles density functional theory and density functional perturbation theory with the local density approximation by the plane-wave pseudopotential method. The band structures are similar to other full-potential calculations. The indirect band gap is about 0.13 eV and decreases with increasing pressure. Simultaneous softening of the M{sub 3} and R{sub 25} zone boundary phonon modes was found and the possible associated successive structural phase transitions were discussed. The mode Grueneisen parameters for optic modes were obtained and the frequency versus pressure relationship was well fitted to second-order polynomials. The quadric relationship between the soft-mode frequency and pressure was also well reproduced for the M{sub 3} and R{sub 25} soft modes. The large difference of the soft-mode-driven transition pressures for the first high-pressure phases of ReO{sub 3} and Cu{sub 3}N were also discussed.
- OSTI ID:
- 20787741
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Vol. 72, Issue 21; Other Information: DOI: 10.1103/PhysRevB.72.214116; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- English
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