We discuss the spin-triplet pairing mechanism induced by the Hund rule ferromagnetic exchange. We include explicitly the e ect of interband hybridization and treat the problem by starting from an extended Hubbard model for a doubly degenerate band, making the simplest Hartree Fock approximation for the part involving the pairing and the Hubbard interaction. The conditions of stability of variou...

We use ab-initio Quantum Mechanics to study the zero temperature phase diagram of BaO. We calculate zero temperature Equations of State of different crystalline phases [B1 (NaCl), B8(NiAs), B2(CsCl), and distorted B2] using Density Functional Theory (DFT) with the generalized gradient approximation (GGA). We find the B1 structure to be the thermodynamically stable one at zero pressure; followed...

The formation of solid-solutions of iodide, bromide, and chloride provides the means to control the structure, band gap, and stability of hybrid halide perovskite semiconductors for photovoltaic applications. We report a computational investigation of the CH3NH3PbI3/CH3NH3PbBr3 alloy from density functional theory with a thermodynamic analysis performed within the generalized quasi-chemical app...

The one-dimensional Hubbard model with different on-site interactions is investigated by renormalization group technique. In the case of a 1/4filled band the dynamical nonequivalence of sites leads to the appearance of Umklapp processes in the system and to the dynamical generation of a gap in the charge excitation spectrum for Ua 6= Ub, Ua > 0 or Ub > 0. The groundstate phase diagram is obtain...

We investigate the ground state phase diagram of the half-filled repulsive Hubbard model in two dimensions in the presence of a staggered potential Delta, the so-called ionic Hubbard model, using cluster dynamical mean-field theory. We find that for large Coulomb repulsion, U >> Delta, the system is a Mott insulator (MI). For weak to intermediate values of Delta, on decreasing U, the Mott gap c...

The MgxZn(1-x)O alloy system may provide an optically tunable family of wide band gap materials that can be used in various UV luminescences, absorption, lighting, and display applications. A systematic investigation of the MgO-ZnO system using ab initio evolutionary simulations shows that MgxZn(1-x)O alloys exist in ordered ground-state structures at pressures above about 6.5 GPa. Detailed ent...

The (001) surface of the emerging photovoltaic material cesium lead triiodide (CsPbI3 ) is studied. Using first-principles methods, we investigate atomic and electronic structure cubic ({\alpha}) orthorhombic ({\gamma}) CsPbI3 . For both phases, find that CsI-termination more stable than PbI2-termination. CsI-terminated surface, then compute analyse phase diagram. We observe surfaces with added...

in this paper a new optical channel drop filter (cdf) based on two dimensional (2-d) photonic crystals (phc) with hexagonal shaped structure is proposed and numerically demonstrated by using the finite-difference-time-domain (fdtd) and plane-wave-expansion (pwe) techniques. photonic crystals (phcs) are artificial dielectric nanostructure materials in which a periodic modulation of the material ...