Ab initio study of structural, electronic, elastic, and phonon properties of ScN and ScP at ambient and high pressure

作者：Pandit Premlata^*; Rakshit Bipul; Sanyal Sankar P

来源：Physica Status Solidi B-Basic Solid State Physics, 2011, 248(4): 921-927.

DOI：10.1002/pssb.201046236

• ab initio calculations
• phonons
• pressure effects
• structure

The structural, electronic, and elastic properties of ScN and ScP in NaCl (B-1 phase) and CsCl (B-2 phase) structures and the phonon dispersion at ambient and high pressure, close to phase transition, have been investigated by using first-principles pseudopotential method in the framework of density functional theory with the generalized gradient approximation. It is found that both compounds are stable in B-1 phase at ambient pressure and undergo a structural phase transition to B-2 phase at 368.76 and 247.56GPa, respectively. ScN is a semiconductor and ScP is semimetallic at ambient pressure (B-1 phase), whereas both the compounds are metallic at high pressure (B-2 phase). The calculated lattice parameter (a), bulk modulus (B), and their first-order pressure derivative (B') are in good agreement with previous calculations. The elastic constants (C-11, C-12, and C-44) have been calculated in both phases. We also report the phonon structure of these compounds at ambient and close to the phase-transition pressure and compared among themselves. It is shown that their phonon structures are consistent with electronic properties at ambient and high pressures. Near B-1-B-2 transition, the LA mode at X-point softens considerably leading to structural instability.