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Microscopic insight into properties and electronic instabilities of impurities in cubic and lower symmetry insulators: the influence of pressure.
The phenomena associated with the Jahn-Teller effect in cubic lattices, the origin of the energy barrier among equivalent minima and the existence of coherent tunnelling in systems like MgO:Cu(2+) are discussed.
Origin of the exotic blue color of copper-containing historical pigments.
The origin of the unusual bright blue color displayed by historical Egyptian Blue and Han Blue pigments that is surprisingly not found in other compounds like BaCuSi2O6 or CaCuO2 containing the same CuO4(6-) chromophore is investigated by means of ab initio calculations.
Impurity-ligand distances derived from magnetic resonance and optical parameters
Non empirical methods for obtaining information from EPR, ENDOR and optical data on the true impurity-ligand distance,R, as well as on the true variations, ΔR, induced by chemical and hydrostatic
Pseudo-Jahn-Teller origin of the low barrier hydrogen bond in N(2)H(7) (+).
The microscopic origin and quantum effects of the low barrier hydrogen bond (LBHB) in the proton-bound ammonia dimer cation N(2)H(7) (+) were studied by means of ab initio and density-functional theory (DFT) methods and a unified view of the Rudle-Pimentel three-center four-electron and charge transfer models of LBHBs is given.
Spectrochemical series and the dependence of Racah and 10 Dq parameters on the metal-ligand distance: microscopic origin.
The microscopic origin of the stronger dependence upon R of 10Dq when compared to that observed for Racah parameters is revealed, thus explaining why electronic transitions which are 10DQ-independent give rise to sharp optical bands.
Changing the Usual Interpretation of the Structure and Ground State of Cu2+-Layered Perovskites
Intense research studies on hybrid organic–inorganic-layered copper perovskites are currently being carried out. Many interesting properties of these materials rest on the strong correlation between
Cr3+-doped fluorides and oxides: role of internal fields and limitations of the Tanabe-Sugano approach.
Surprising results are found that are shown to arise from the deformation of both 3d(Cr) and ligand orbitals in the antibonding e(g) orbital, which has a σ character and is more extended than the π t(2 g) orbital.
Colour due to Cr3+ ions in oxides: a study of the model system MgO:Cr3+.
The calculated electrostatic potential, VR(r), related to ER(r,), is found to be attractive when the electronic density is lying along <110> directions and |r| > 1 Å driven by the first shell of twelve Mg(2+) ions.
Key Role of Covalent Bonding in Octahedral Tilting in Perovskites
Although crystals with perovskite structure have been intensively investigated, there is up to now no clear explanation of why some of them do not remain cubic at low temperature. In particular, the