We investigate the quantum phase transitions in half-filled Hubbard model on triangular lattice by means of path-integral renormalization group method with a new iteration and truncation scheme proposed recently. It is found for cluster 36 sites that as interaction U increases, paramagnetic metallic state undergoes first-order transition to nonmagnetic insulating (NMI) at Uc1 approximately 7.4t, which followed another 120 degrees Néel ordered Uc2 9.2t, where t transfer integral. The size...

Quantum computers are expected to accelerate solving combinatorial optimization problems, including algorithms such as Grover adaptive search and quantum approximate algorithm (QAOA). However, many problems involve constraints which, when imposed soft in the cost function, can negatively impact performance of algorithm. In this paper, we propose fermionic (FQAOA) for with constraints. Specifically, FQAOA tackles constrains issue by using fermion particle number preservation intrinsically...

Trifluoromethyl diethylaminosulfur difluoride (CF3-DAST) was found to be an efficient reagent for the trifluoromethylthiolation of α-methylene-β-keto esters providing α-trifluoromethylthio-β-keto in good high yields. α-Methylene-β-keto sulfones were also accepted as substrates by CF3-DAST furnish corresponding α-trifluoromethylthio compounds. This strategy can extended perfluoroalkylthiolation reactions using perfluoroethyl-DAST (C2F5-DAST) and perfluoropropyl-DAST (C3F7-DAST).

To reveal the role of Fe sublattice in coercivity R2Fe14B, we investigated origin perpendicular magnetocrystalline anisotropy (MCA) Y2Fe14B using first-principles density-functional calculations. We found that MCA arises predominantly from sites with higher symmetry (16k1,2 and 8j1,2). On other hand, Fe(4c) show a significant contribution to in-plane MCA. This can be attributed localized character Fe(4c)-d orbitals R2Fe14B. Furthermore, energy increases as number valence electrons within...

Exciton Mott physics in two-dimensional electron-hole (e-h) systems is studied the quasiequilibrium, which crossovers or phase transitions between insulating exciton gas and metallic e-h plasma. By developing a self-consistent screened T-matrix approximation, we succeed obtaining "global" diagram on plane of density temperature as contour plot ionization ratio. The detailed features exciton-Mott crossover at high are figured out beyond conventionally used concept density. At low temperature,...

We study the local magnetic anisotropy due to Nd ions located around surfaces of <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Fe xmlns:xlink="http://www.w3.org/1999/xlink">14</sub> B within crystal field theory based on first-principles calculations. The (001) surface exhibit A <sup xmlns:xlink="http://www.w3.org/1999/xlink">0</sup> <; 0, that is, in-plane anisotropy, as reported previously, but those (100) > which is consistent with...

The local magnetic anisotropy of R ions in R2Fe14B (R = Dy, Ho) systems is studied based on a microscopic effective spin model constructed from the information obtained by using first-principles calculations. By taking into account up to 6-th order crystal electric field parameters, satisfactory describes observed magnetization curves and temperature dependence constants. We found that at low temperatures, noncollinear structure appears Ho2Fe14B system reflecting anisotropy.

A trifluoromethyl analogue of diethylaminosulfur trifluoride (CF3-DAST)-induced deacylative trifluoromethylthiolation cyclic 1,3-diketones, lactams, and lactones that provides α-trifluoromethylthioketones, is reported. To the best our knowledge, this method represents first example lactams. corresponding pentafluorophenylthiolation using a pentafluorophenyl (C6F5-DAST) was also attempted.

The mechanisms underlying the enhancement of magnetic anisotropies (MAs) Sm ions, owing to valence electrons at site and screened nuclear charges ligands, are clarified using a detailed analysis crystal fields (CF). In order investigate finite-temperature properties, we developed an effective spin model for $\mathrm{Sm}{\mathrm{Fe}}_{12}X$ ($X$=H, B, C, N) $\mathrm{Sm}{\mathrm{Fe}}_{11}M$ ($M$=Ti, V, Co), where moments, CF parameters, exchange were determined by first-principle calculations....

We investigate the correlation effect in quasi-one-dimensional electron-hole ($e\mathrm{\text{\ensuremath{-}}}h$) system under thermal equilibrium. A self-consistent screened $T$-matrix approximation developed here enables description of an $e\mathrm{\text{\ensuremath{-}}}h$ pair any ionization ratio, portion quasielectrons or quasiholes moving almost freely. Our phase diagram on ratio provides a unified exciton Mott physics from low-density gas towards high-density plasma, and predicts...

We investigate the bandwidth-controlled Mott transition in Hubbard model on checkerboard lattice at half filling using path-integral renormalization group (PIRG) method. It is demonstrated that system undergoes a first-order phase to plaquette-singlet insulating finite interaction. This conclusion drawn via detailed analysis of spin and charge correlations around point by means PIRG method aided with new iteration scheme introduced this paper.

A new method to calculate the crystal field parameters (CFPs) is first applied crystalline Nd2Fe14B as representative of rare-earth iron boron permanent magnets. The CFPs are extracted from one electron Hamiltonian expressed in basis Wannier functions. low energy properties 4f orbitals and influence hybridization with Fe(3d) investigated by solving eigenvalue problems. Authors have found fundamental property; more cloud expanded a–b plane, single-ion anisotropy along c-axis increases....

To investigate the magnetic properties of SmFe$_{12}$, we construct an effective spin model, where moments, crystal field (CF) parameters, and exchange fields at 0 K are determined by first principles. Finite temperature investigated using this model. We further develop analytical method with strong mixing states different quantum number angular momentum $J$ ($J$-mixing), which is caused acting on component 4$f$ electrons. Comparing our results those calculated Boltzmann statistics, clarify...

We study the ground-state properties of geometrically frustrated Hubbard model on anisotropic checkerboard lattice with nearest-neighbor hopping $t$ and next-nearest-neighbor ${t}^{\ensuremath{'}}$. By using path-integral renormalization-group method, we phase diagram in parameter space interaction $U$ frustration-control ${t}^{\ensuremath{'}}/t$. Close examinations effective hopping, double occupancy, momentum distribution, spin- charge-correlation functions allow us to determine at zero...

We study quasi-one-dimensional electron-hole (e-h) systems by applying a self-consistent screened $T$-matrix approximation (SSTA), which can treat an e-h pair embedded in the background of exciton-plasma mixture, characterized exciton ionization ratio. Two classical-quantum crossovers are found. The first crossover takes place as drastic suppression ratio, representing onset quantum dissociation (binding-energy reduction and level-broadening effects). second one be seen gradual change...

A real-space representation of the uniaxial magnetic anisotropy (MA) metallic ferromagnets is formulated using full-orbital tight-binding model. By adopting a second-order perturbation for spin-orbit interaction, numerical calculations MA are performed L10 FePt and Y2Fe14B compounds to evaluate validity applicability present method.

When using the indirect method in magnetostatic analysis, magnetic material is represented by double-layer charge on surface. The offers an integral form of scalar potential to give a boundary equation (BIE). A unified excitation has been derived, resulting BIE capable solving generic problems. we apply standard analyze shields thin shells with high permeability, usually cannot get accurate results shielded space. To accurately solve shielding problems rough meshes, this paper propose new...

We investigate a frustrated Ising spin system on the garnet lattice composed of specific network corner-sharing triangles. By means Monte Carlo simulations with heat bath algorithm, we discuss magnetic properties at finite temperatures. It is shown that nearest-neighbor couplings does not exhibit any transitions, yielding large residual entropy zero temperature. also effect long-range dipolar interaction systematically to determine phase diagram model lattice. find there appear variety...

In this study, we investigate the finite-temperature magnetic properties of Sm2Fe17Nx (x = 0,3) using an effective spin model constructed based on information obtained by first-principles calculations. We find that assuming plausible trivalent Sm3+ configuration results in a can satisfactorily describe magnetization curves Sm2Fe17N3. By contrast, divalent Sm2+ is suitable to reproduce Sm2Fe17. These expand understanding how electronic structure affects these compounds.

It has been empirically known that the coercivity of rare-earth permanent magnets depends on size and shape fine particles main phase in system. Also, recent experimental observations have suggested atomic-scale structures around grain-boundaries play a crucial role to determine their switching fields. In this article, we review theoretical attempt describe finite temperature magnetic properties evaluate reduction fields several materials based an atomistic spin model is constructed using...

We study the superconducting transition near half-filling of electron-doped cuprates with so-called T'-structure based on an effective two-band model using fluctuation-exchange approximation and solving linearized Eliashberg equation. find d-wave superconductivity even at this when energy difference between upper Hubbard level Cu orbitals O 2p levels is less than about 1.5eV, which plausible for T'-type cuprates.

Magnetization curves for Nd2Fe14B single crystals were measured between 300 K and 900 K. The saturation magnetization Ms along the [100] direction was found to be 2% 4% smaller than that [001] direction, not only at but also up Curie temperature. We attributed this difference in reduction of Nd moment when forced aligned by external fields. Significant anisotropy observed paramagnetic susceptibility χ Based on crystalline electric field parameters obtained first-principles calculation, we...