Yamamoto, Keisuke, Todo, Synge, Miyashita, Seiji
We study the finite temperature properties of the extended Bose-Hubbard model on a cubic lattice. This model exhibits the so-called supersolid state. To start with, we investigate ordering processes...
De Raedt, Hans, De Raedt, Koen, Michielsen, Kristel, Keimpema, Koenraad, Miyashita, Seiji
Inspired by Einstein-Podolsky-Rosen-Bohm experiments with photons, we construct an event-based simulation model in which every essential element in the ideal experiment has a counterpart. The model...
Slow Relaxation due to Entropy Effect -- Entropic Slowing Down -- (2007)
We study entropic slowing down in a decorated bond system. Though it is commonly known that complicate energy landscape in random spin systems causes slow relaxation, we find that the slowing down...
Realization of the mean-field universality class in spin-crossover materials (2007)
Miyashita, Seiji, Konishi, Yusuké, Nishino, Masamichi, Tokoro, Hiroko, Rikvold, Per Arne
In spin-crossover materials, the volume of a molecule changes depending on whether it is in the high-spin (HS) or low-spin (LS) state. This change causes distortion of the lattice. Elastic...
Monte Carlo simulation of pressure-induced phase transitions in spin-crossover materials (2007)
Konishi, Yusuke, Tokoro, Hiroko, Nishino, Masamichi, Miyashita, Seiji
Pressure-induced phase transitions of spin-crossover materials were simulated by a Monte Carlo simulation in the constant pressure ensemble for the first time. Here, as the origin of the cooperative...
Directionally Independent Energy Gap Formation Due to the Hyperfine Interaction (2003)
We study energy gap formation at the level-crossing point due to the hyperfine interaction. In contrast to the energy gap induced by the Dzyaloshinskii-Moriya interaction, the gap induced by the...
Quantum Mechanical Transitions in a Dissipative Environment (2000)
We have constructed an algorithm to treat quantum mechanical dynamics, such as the nonadiabatic transitions in a dissipative environment, by making use of the formula of reduced density matrix, i.e.,...
Quantum Dynamics in Nanoscale Magnets in Dissipative Environments (2000)
In discrete energy structure of nanoscale magnets, nonadiabatic transitions at avoided level crossings lead to fundamental processes of dynamics of magnetizations. The thermal environment causes...
Nontrivial Response of Nanoscale Uniaxial Magnets to an Alternating Field (1998)
The response of nanoscale uniaxial magnets to an alternating field is studied by direct numerical calculation. A nontrivial oscillation of the magnetization is found and subsequently analyzed in...
Takasu, Masako, Miyashita, Seiji, Suzuki, Masuo, Kanada, Yasumasa
The S = 1/2 ferromagnetic XY model on the triangular lattice is investigated by quantum Monte Carlo methods based on the Suzuki-Trotter formula. The squared magnetization (M2x) / N2 is calculated for...
Ordering process of the antiferromagnetic Heisenberg model on the square is investigated mainly by a quantum Monte Carlo method. The effect of quantum fluctuation is studied by investigating the...
Takasu, Masako, Miyashita, Seiji, Suzuki, Masuo, Kanada, Yasumasa
The S = 1/2 ferromagnetic XY model on the triangular lattice is investigated by quantum Monte Carlo methods based on the Suzuki-Trotter formula. The squared magnetization (M2x) / N2 is calculated for...
Ordering process of the antiferromagnetic Heisenberg model on the square is investigated mainly by a quantum Monte Carlo method. The effect of quantum fluctuation is studied by investigating the...
Takasu, Masako, Miyashita, Seiji, Suzuki, Masuo, Kanada, Yasumasa
The S = 1/2 ferromagnetic XY model on the triangular lattice is investigated by quantum Monte Carlo methods based on the Suzuki-Trotter formula. The squared magnetization (M2x) / N2 is calculated for...
Ordering process of the antiferromagnetic Heisenberg model on the square is investigated mainly by a quantum Monte Carlo method. The effect of quantum fluctuation is studied by investigating the...