Piezoelectricity in gadolinium ferrite: A computational study

Douglas-Koll-Hess (DKH) second-order relativistic scalar approach was used to investigate piezoeletricity in gadolinium ferrite (GdFeO3). To adequately represent the polyatomic environment studied – (24s13p), (29s17p12d) and (32s22p16d10f)– basis sets were built for the atoms O (3P), Fe (5D), and Gd (9D), then contracted to [4s2p], [12s6p5d], and [19s12p8d4f], respectively. The qualifying of the contracted basis sets for GdFeO3 crystal studies was conducted in three moments, namely: quality evaluation in molecular calculations, made in 1FeO1+ and 1GdO1+ molecular fragments; the choice of polarization function used in the [4s2p] basis set for O (3P) atom; the choice of diffuse functions used in the [12s6p5d] and [19s12p8d4f] basis sets for Fe (5D) and Gd (9D) atoms, respectively. The qualified contracted basis sets gave rise to the molecular [4s2p1d]/[13s7p6]/[20s13p9d5f] basis set which was then used to describe geometric parameters of the GdFeO3 crystal. The good performance of the [4s2p1d]/[13s7p6d]/[20s13p9d5f] basis set in describing the geometry of the material of interest led to calculations of the material properties: total relativistic energy, dipole moment and total atomic charge. The analysis of the results for these properties showed that the possible piezoelectricity in GdFeO3 can be caused by electrostatic interactions of its atoms.