We have investigated the electronic, structural, and dielectric properties of the ferroelectric Sn2P2Se6 using the local density approximation of the density functional theory. The charge density analysis reveals the existence of isolated [P2Se6] groups and Sn atoms, which are weakly bonded to each other. The band structure is made of weakly dispersive bands, which are assigned to different atomic and/or molecular orbitals. The electronic gap is on the order of ∼ 1 eV. The theoretical determination of the structure underestimates the unit cell parameters (up to 6%) and the Sn-Se interatomic bond distances (up to 11%) with respect to the experimental results, while the agreement is excellent (within 1% for bond lengths) in the description of the [P2Se6] group geometry. The Born effective charges of P and Se are much more anisotropic than those of Sn. The computed spontaneous polarization is on the order of 15 μC cm-2.
|Number of pages||7|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 1 Sep 2002|