Investigation of the multiplet features of SrTiO3in X-ray absorption spectra based on configuration interaction calculations

Synchrotron-basedL2,3-edge absorption spectra show strong sensitivities to the local electronic structure and chemical environment. However, detailed physical information cannot be extracted easily without computational aids. Here, using the experimental TiL2,3-edges absorption spectrum of SrTiO3as a fingerprint and considering full multiplet effects, calculations yield different energy parameters characterizing local ground state properties. The peak splitting and intensity ratios of theL3andL2set of peaks are carefully analyzed quantitatively, giving rise to a small hybridization energy around 1.2 eV, and the different hybridization energy values reported in the literature are further addressed. Finally, absorption spectra with different linearly polarized photons under various tetragonal crystal fields are investigated, revealing a non-linear orbital–lattice interaction, and a theoretical guidance for material engineering of SrTiO3-based thin films and heterostructures is offered. Detailed analysis of spectrum shifts with different tetragonal crystal fields suggests that theegcrystal field splitting is a necessary parameter for a thorough analysis of the spectra, even though it is not relevant for the ground state properties.

The Contribution of the Bulk Modes on Electrical Conductivity in 3D Topological Insulators

Determination of transport coefficients in 3D topological insulators is one of the highlighted topics in the literature. The main difficulty of the calculation of transport coefficients comes from the contribution of bulk modes. In this work, electrical conductivity in 3D topologic insulators is considered under zero magnetic fields and it is written in a size dependent form. For this purpose, Weyl conjecture is used. The contribution of the bulk modes to electrical conductivity is analytically derived by depending on the material size, hybridization energy and degeneracy of the carriers.

Binding Sites of miR-1273 Family on the mRNA of Target Genes

This study examined binding sites of 2,578 miRNAs in the mRNAs of 12,175 human genes using the MirTarget program. It found that the miRNAs of miR-1273 family have between 33 and 1,074 mRNA target genes, with a free hybridization energy of 90% or more of its maximum value. The miR-1273 family consists of miR-1273a, miR-1273c, miR-1273d, miR-1273e, miR-1273f, miR-1273g-3p, miR-1273g-5p, miR-1273h-3p, and miR-1273h-5p. Unique miRNAs (miR-1273e, miR-1273f, and miR-1273g-3p) have more than 400 target genes. We established 99 mRNA nucleotide sequences that contain arranged binding sites for the miR-1273 family. High conservation of each miRNA binding site in the mRNA of the target genes was found. The arranged binding sites of the miR-1273 family are located in the 5′UTR, CDS, or 3′UTR of many mRNAs. Five repeating sites containing some of the miR-1273 family’s binding sites were found in the 3′UTR of several target genes. The oligonucleotide sequences of miR-1273 binding sites located in CDSs code for homologous amino acid sequences in the proteins of target genes. The biological role of unique miRNAs was also discussed.

ELECTRONIC PROPERTIES OF STRONGLY CORRELATED SYSTEMS

The observation that the energy scale of the magnetic excitations determined by the Heisenberg coupling constant ( J ≈ 0.1eV ) is much smaller than the charge excitation energies (≳ 2eV ) places the stoichiomatic Cu-oxides with formal valence Cu 2+ in the class of Mott insulators. Holes introduced into the CuO 2 layers can therefore be described by an effective Hamiltonian which contains a hopping term for holes between nearest neighbor CuO 4-squares (matrix element, t ) in addition to the Heisenberg term1). This effective Hamiltonian is restricted to the Hilbert subspace with one or less electrons in the Wannier orbital on each CuO 4 square. The Wannier orbital is made up from the [Formula: see text] Cu-orbital and a combination of the 2p O-orbitals with the same symmetry. The hybridization energy is maximized for a hole by forming a spin singlet combination of these orbitals so that the form of the effective Hamiltonian does not differ in form2) from that of a single band Hubbard model in the strongly correlated limit. The inclusion of O-O hopping does not change this conclusion3). Estimates of the parameter t , give a value t ≈ 0.5eV so that the ratio J/t ≪ l .