Ground state properties of heavy alkali halides

We extend previous work on alkali halides by calculations for the heavy-atom species RbF, RbCl, LiBr, NaBr, KBr, RbBr, LiI, NaI, KI, and RbI. Relativistic effects are included by means of energy-consistent pseudopotentials, correlations are treated at the coupled-cluster level. A striking deficiency of the Hartree-Fock approach are lattice constants deviating by up to 7.5 % from experimental values which is reduced to a maximum error of 2.4 % by taking into account electron correlation. Besides, we provide ab-initio data for in-crystal polarizabilities and van der Waals coefficients.Comment: accepted by Phys. Rev.

High-pressure crystal structure, lattice vibrations, and band structure of BiSbO4

"This document is the Accepted Manuscript version of a Published Work that appeared in final form in Inorganic Chemistry, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://dx.doi.org/10.1021/acs.inorgchem.6b00503”The high-pressure crystal structure, lattice-vibrations HP crystal structure, lattice vibrations, and band , and electronic band structure of BiSbO4 were studied by ab initio simulations. We also performed Raman spectroscopy, infrared spectroscopy, and diffuse-reflectance measurements, as well as synchrotron powder X-ray diffraction. High-pressure X-ray diffraction measurements show that the crystal structure of BiSbO4 remains stable up to at least 70 GPa, unlike other known MTO4-type ternary oxides. These experiments also give information on the pressure dependence of the unit-cell parameters. Calculations properly describe the crystal structure of BiSbO4 and the changes induced by pressure on it. They also predict a possible high-pressure phase. A room-temperature pressure volume equation of state is determined, and the effect of pressure on the coordination polyhedron of Bi and Sb is discussed. Raman- and infrared-active phonons were measured and calculated. In particular, calculations provide assignments for all the vibrational modes as well as their pressure dependence. In addition, the band structure and electronic density of states under pressure were also calculated. The calculations combined with the optical measurements allow us to conclude that BiSbO4 is an indirect-gap semiconductor, with an electronic band gap of 2.9(1) eV. Finally, the isothermal compressibility tensor for. BiSbO4 is given at 1.8 GPa. The experimental (theoretical) data revealed that the direction of maximum compressibility is in the (0 1 0) plane at similar to 33 degrees (38 degrees) to the c-axis and 47 degrees (42 degrees) to the a-axis. The reliability of the reported results is supported by the consistency between experiments and calculations.Research supported by the Spanish government MINECO under Grant Nos. MAT2013-46649-C4-1/2/3-P and MAT2015-71070-REDC. We also acknowledge the computer time provided by MALTA cluster and the Red Espanola de Supercomputacion. Experiments were performed at MSPD beamline at ALBA Synchrotron Light Facility with the collaboration of ALBA staff.Errandonea, D.; Muñoz, A.; Rodríguez-Hernández, P.; Gomis, O.; Achary, SN.; Popescu, C.; Patwe, SJ.... (2016). High-pressure crystal structure, lattice vibrations, and band structure of BiSbO4. Inorganic Chemistry. 55(10):4958-4969. doi:10.1021/acs.inorgchem.6b00503S49584969551