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...
Improved chain mean-field theory for quasi-one-dimensional quantum magnets (2008)
A novel mean-field approximation for quasi-one-dimensional (Q1D) quantum magnets is formulated. Our new mean-field approach is based on the Bethe-type effective-field theory, where thermal and...
Green's function theory for spin-1/2 ferromagnets with an easy-plane exchange anisotropy (2008)
Yamamoto, Daisuke, Todo, Synge, Kurihara, Susumu
The many-body Green's function theory with the random-phase approximation is applied to the study of easy-plane spin-1/2 ferromagnets in an in-plane magnetic field. We demonstrate that the usual...
Order-N Cluster Monte Carlo Method for Spin Systems with Long-range Interactions (2008)
An efficient O(N) cluster Monte Carlo method for Ising models with long-range interactions is presented. Our novel algorithm does not introduce any cutoff for interaction range and thus it strictly...
Parity law of the singlet-triplet gap in graphitic ribbons (2006)
Al Hajj, Mohamad, Alet, Fabien, Capponi, Sylvain, Lepetit, Marie Bernadette, Malrieu, Jean-Paul, Todo, Synge
This work explores the possibility to transfer the parity law of the singlet-triplet gap established for square ladders (gapped for even number of legs, gapless for odd number of legs) to fused...
Parity law of the singlet-triplet gap in graphitic ribbons (2006)
Al Hajj, Mohamad, Alet, Fabien, Capponi, Sylvain, Lepetit, Marie Bernadette, Malrieu, Jean-Paul, Todo, Synge
This work explores the possibility to transfer the parity law of the singlet-triplet gap established for square ladders (gapped for even number of legs, gapless for odd number of legs) to fused...
Bond-Dilution-Induced Quantum Phase Transitions in Heisenberg Antiferromagnets (2006)
Yasuda, Chitoshi, Todo, Synge, Takayama, Hajime
Bond-dilution effects on the ground state of the square-lattice antiferromagnetic Heisenberg model, consisting of coupled bond-alternating chains, are investigated by means of the quantum Monte Carlo...
Universal Reduction of Effective Coordination Number in the Quasi-One-Dimensional Ising Model (2006)
Critical temperature of quasi-one-dimensional general-spin Ising ferromagnets is investigated by means of the cluster Monte Carlo method performed on infinite-length strips, L times infty or L times...
Parity law of the singlet-triplet gap in graphitic ribbons (2006)
Al Hajj, Mohamad, Alet, Fabien, Capponi, Sylvain, Lepetit, Marie Bernadette, Malrieu, Jean-Paul, Todo, Synge
This work explores the possibility to transfer the parity law of the singlet-triplet gap established for square ladders (gapped for even number of legs, gapless for odd number of legs) to fused...
Parity law of the singlet-triplet gap in graphitic ribbons (2006)
Hajj, Mohamad Al, Alet, Fabien, Capponi, Sylvain, Lepetit, Marie Bernadette, Malrieu, Jean-Paul, Todo, Synge
This work explores the possibility to transfer the parity law of the singlet-triplet gap established for square ladders (gapped for even number of legs, gapless for odd number of legs) to fused...
Parity law of the singlet-triplet gap in graphitic ribbons (2006)
Al Hajj, Mohamad, Alet, Fabien, Capponi, Sylvain, Lepetit, Marie Bernadette, Malrieu, Jean-Paul, Todo, Synge
This work explores the possibility to transfer the parity law of the singlet-triplet gap established for square ladders (gapped for even number of legs, gapless for odd number of legs) to fused...
Parity law of the singlet-triplet gap in graphitic ribbons (2006)
Al Hajj, Mohamad, Alet, Fabien, Capponi, Sylvain, Lepetit, Marie Bernadette, Malrieu, Jean-Paul, Todo, Synge
This work explores the possibility to transfer the parity law of the singlet-triplet gap established for square ladders (gapped for even number of legs, gapless for odd number of legs) to fused...
Quantum phase transitions of spin chiral nanotubes (2005)
Matsumoto, Munehisa, Sakai, Toru, Sato, Masahiro, Takayama, Hajime, Todo, Synge
Recently many interesting magnetic nanostructures have been fabricated and much attention is arising on the rich magnetic properties that originate in the quantum effects eminent in the nanoscale...
Randomness-driven quantum phase transition in bond-alternating Haldane chain (2004)
Arakawa, Takayuki, Todo, Synge, Takayama, Hajime
The effect of bond randomness on the spin-gapped ground state of the spin-1 bond-alternating antiferromagnetic Heisenberg chain is discussed. By using the loop cluster quantum Monte Carlo method, we...
Quantum Phase Transitions of Quasi-One-Dimensional Heisenberg Antiferromagnets (2003)
Matsumoto, Munehisa, Todo, Synge, Yasuda, Chitoshi, Takayama, Hajime
We study the ground-state phase transitions of quasi-one-dimensional quantum Heisenberg antiferromagnets by the quantum Monte Carlo method with the continuous-time loop algorithm and finite-size...
Melting of Stripes in a Two-Dimensional Hard-Core Boson Hubbard Model (2003)
Schmid, Guido, Todo, Synge, Troyer, Matthias, Batrouni, G. George
Matsumoto, Munehisa, Todo, Synge, Nakamura, Masaaki, Yasuda, Chitoshi, Takayama, Hajime
We have proposed the plaquette-singlet solid (PSS) ground state for the spin-1 antiferromagnetic Heisenberg two-leg ladder. Based on the PSS picture, we discuss the correspondence of the PSS state to...
Yasuda, Chitoshi, Todo, Synge, Matsumoto, Munehisa, Takayama, Hajime
Dilution effects on spin-1/2 quantum Heisenberg antiferromagnets with a non-magnetic spin-gapped ground state are studied by means of the qunatum Monte Carlo simulation. In the site-diluted system,...
Novel Order Parameter to Characterize Valence-Bond-Solid States (2002)
Nakamura, Masaaki, Todo, Synge
We propose an order parameter to characterize valence-bond-solid (VBS) states in quantum spin chains, given by the ground-state expectation value of a unitary operator appearing in the...
Order Parameter to Characterize Valence-Bond-Solid States in Quantum Spin Chains (2001)
Nakamura, Masaaki, Todo, Synge
We propose an order parameter to characterize valence-bond-solid (VBS) states in quantum spin chains, given by the ground-state expectation value of a unitary operator appearing in the...
Finite-Temperature Phase Diagram of Hard-Core Bosons in Two Dimensions (2001)
Schmid, Guido, Todo, Synge, Troyer, Matthias, Dorneich, Ansgar
We determine the finite-temperature phase diagram of the square lattice hard-core boson Hubbard model with nearest neighbor repulsion using quantum Monte Carlo simulations. This model is equivalent...
Bond-Dilution Effects on Two-Dimensional Spin-Gapped Heisenberg Antiferromagnets (2001)
Yasuda, Chitoshi, Todo, Synge, Matsumoto, Munehisa, Takayama, Hajime
Bond-dilution effects on spin-1/2 spin-gapped Heisenberg antiferromagnets of coupled alternating chains on a square lattice are investigated by means of the quantum Monte Carlo method. It is found...
Matsumoto, Munehisa, Yasuda, Chitoshi, Todo, Synge, Takayama, Hajime
The S=1/2 and S=1 two-dimensional quantum Heisenberg antiferromagnets on the anisotropic dimerized square lattice are investigated by the quantum Monte Carlo method. By finite-size-scaling analyses...
Koikegami, Shigeru, Todo, Synge, Takayama, Hajime
We investigate S=1 antiferromagnetic quantum spin chain, whose exchange couplings are strongly disordered. By the real-space renomalization group method, introduced by Ma, Dasgupta, and Hu, the...
Todo, Synge, Matsumoto, Munehisa, Yasuda, Chitoshi, Takayama, Hajime
Ground-state properties of the spin-1 two-leg antiferromagnetic ladder are investigated precisely by means of the quantum Monte Carlo method. It is found that the correlation length along the chains...
Yasuda, Chitoshi, Todo, Synge, Matsumoto, Munehisa, Takayama, Hajime
Effects of the site dilution on spin-gapped Heisenberg antiferromagnets with $S=1/2$ and S=1 on a square lattice are investigated by means of the quantum Monte Carlo method. It is found that...
Cluster algorithms for general-S quantum spin systems (1999)
We present a general strategy to extend quantum cluster algorithms for S=1/2 spin systems, such as the loop algorithm, to systems with arbitrary size of spins. In general, the partition function of a...
Quantum Monte Carlo Study of Random Antiferromagnetic Heisenberg Chain (1998)
Todo, Synge, Kato, Kiyoshi, Takayama, Hajime
Effects of randomness on the spin-1/2 and 1 antiferromagnetic Heisenberg chains are studied using the quantum Monte Carlo method with the continuous-time loop algorithm. We precisely calculated the...
Transfer-Matrix Study of Hard-Core Singularity for Hard-Square Lattice Gas (1997)
A singularity on the negative fugacity axis of the hard-square lattice gas is investigated in terms of numerical diagonalization of transfer matrices. The location of the singular point $z_c^-$ and...