Related papers: Collective excitations in Na$_2$IrO$_3$
We investigate the electronic states and the transport properties of the CoO2 plane in NaxCoO2 on the basis of the two-dimensional triangular lattice 11-band d-p model by using the fluctuation exchange approximation, where we consider the…
The exchange interaction is investigated theoretically for electrons confined to a 2-D sample placed in a linearly varying magnetic field perpendicular to the plane. Unusual and interesting behavior is predicted: starting from zero, as one…
We analyze the resonant x-ray scattering (RIXS) spectra from Sr$_2$IrO$_4$ in an itinerant electron approach. Employing a multi-orbital tight-binding model on the square lattice, we calculate the one-electron energy band within the…
We theoretically study the collective excitations of a spin-orbit-coupled spin-1 Bose-Einstein condensate with antiferromagnetic spin-exchange interactions in a cigar-shaped trapping potential at zero and finite temperatures using the…
The multi-configuration Dirac-Hartree-Fock method was employed to calculate the total and excitation energies, oscillator strengths and hyperfine structure constants for low-lying levels of Sm I. In the first-order perturbation…
The density of states of a Bose-condensed gas confined in a harmonic trap is investigated. The predictions of Bogoliubov theory are compared with the ones of Hartree-Fock theory and of the hydrodynamic model. We show that the Hartree-Fock…
We investigate the electronic structure of BaIrO3, an interesting compound exhibiting charge density wave transition in its insulating phase and ferromagnetic transition at the same temperature, using full potential linearized augmented…
This work merges two different types of many-electron ensembles, namely the Theophilou-Gross-Oliveira-Kohn ensembles of ground and neutrally-excited states, and the more recent $N$-centered ensembles of neutral and charged ground states. On…
We study low-lying collective modes of a horizontally elongated 87Rb condensate produced in a 3D magnetic harmonic trap with the addition of a 1D periodic potential which is provided by a laser standing-wave along the horizontal axis. While…
In the Mott-Hubbard insulators YTiO3 and SmTiO3 we study optical excitations from the lower to the upper Hubbard band, d^1d^1 -> d^0d^2. The multi-peak structure observed in the optical conductivity reflects the multiplet structure of the…
A theory of heterostructures comprised of LaTiO$_3$ (a Mott insulator) and SrTiO$_3$ (a band insulator) is presented. The band structure of the Ti $d$% -electrons is treated with a nearest neighbor tight-binding approximation; the electric…
Contrary to previous studies that classify Na2IrO3 as a realization of the Heisenberg-Kitaev model with dominant spin-orbit coupling, we show that this system represents a highly unusual case in which the electronic structure is dominated…
We measured high resolution Cu $L_3$ edge resonant inelastic x-ray scattering (RIXS) of the undoped cuprates La$_2$CuO$_4$, Sr$_2$CuO$_2$Cl$_2$, CaCuO$_2$ and NdBa$_2$Cu$_3$O$_6$. The dominant spectral features were assigned to $dd$…
The electronic structure of Na$_x$CoO$_2$ revealed by recent photoemission experiments shows important deviations from band theory predictions. The six small Fermi surface pockets predicted by LDA calculations have not been observed as the…
The one-band Hubbard model at half-filling on a truncated tetrahedron (C$_{12}$), and on the C$_{60}$ molecule is studied. Within the Hartree-Fock approximation, we find a magnetic-like instability of the `Fermi sea' towards a spin-ordered…
We study two Heisenberg-Kitaev t-J-like models on a honeycomb lattice, focusing on the zigzag magnetic phase of Na$_2$IrO$_3$, and investigate hole motion by exact diagonalization and variational methods. The spectral functions are quite…
Collective excited states form in organic two-dimensional layers through the Coulomb coupling of the molecular transition dipole moments. They manifest as characteristic strong and narrow peaks in the excitation and emission spectra that…
We study the elementary excitations in 5d transition metal oxideSr$_2$IrO$_4$ by calculating the particle-hole Green's function within the random phase approximation on an antiferromagnetic ground state in the two-dimensional multi-orbital…
Calculating charge transfer (CT) excitation energies with high accuracy and low computational cost is a challenging task. Kohn-Sham density functional theory (KS-DFT), due to its efficiency and accuracy, has achieved great success in…
We present a theory of the quasi two-dimensional electron gas (2DEG) systems which appear near the surface of SrTiO$_3$ when a large external electric field attracts carriers to the surface. We find that non-linear and non-local screening…