Otsuka, Yuichi, Seo, Hitoshi, Motome, Yukitoshi, Kato, Takeo
We investigate ground state properties of a quasi-one-dimensional electron-lattice coupled model for quarter-filled molecular conductors. The effective one-dimensional extended Hubbard model coupled...
Spiral charge frustration in molecular conductor (DI-DCNQI)2Ag (2008)
Seo, Hitoshi, Motome, Yukitoshi
We theoretically study the effect of spiral-type charge frustration in a quasi-one-dimensional molecular conductor (DI-DCNQI)2Ag. We clarify how the spiral frustration in the interchain Coulomb...
Otsuka, Yuichi, Seo, Hitoshi, Motome, Yukitoshi, Kato, Takeo
Finite-temperature phase transitions in quasi-one-dimensional quarter-filled systems are investigated by the extended Hubbard model with electron-lattice coupling. Using a quantum Monte Carlo method...
Single-Component Molecular Metals as Multiband \pi-d Systems (2008)
Seo, Hitoshi, Ishibashi, Shoji, Okano, Yoshinori, Kobayashi, Hayao, Kobayashi, Akiko, Fukuyama, Hidetoshi, ...
Electronic states of single-component molecular metals M(tmdt)2 (M = Ni, Au) are studied theoretically. We construct an effective three-band Hubbard model for each material by numerical fitting to...
Charge-Ordered State versus Dimer-Mott Insulator at Finite Temperatures (2007)
Yoshioka, Hideo, Tsuchiizu, Masahisa, Seo, Hitoshi
We theoretically investigate the competition between charge-ordered state and Mott insulating state at finite temperatures in quarter-filled quasi-one-dimensional electron systems, by studying...
Finite-temperature phase transitions in quasi-one-dimensional molecular conductors (2006)
Seo, Hitoshi, Motome, Yukitoshi, Kato, Takeo
Phase transitions in 1/4-filled quasi-one-dimensional molecular conductors are studied theoretically on the basis of extended Hubbard chains including electron-lattice interactions coupled by...
Charge Fluctuations in Geometrically Frustrated Charge Ordering System (2006)
Seo, Hitoshi, Tsutui, Kenji, Ogata, Masao, Merino, Jaime
Effects of geometrical frustration in low-dimensional charge ordering systems are theoretically studied, mainly focusing on dynamical properties. We treat extended Hubbard models at quarter-filling,...
Yoshioka, Hideo, Tsuchiizu, Masahisa, Seo, Hitoshi
Finite-temperature charge-ordering phase transition in quasi one-dimensional (1D) molecular conductors is investigated theoretically, based on a quasi 1D extended Hubbard model at quarter filling...
Theoretical Aspects of Charge Ordering in Molecular Conductors (2006)
Seo, Hitoshi, Merino, Jaime, Yoshioka, Hideo, Ogata, Masao
Theoretical studies on charge ordering phenomena in quarter-filled molecular (organic) conductors are reviewed. Extended Hubbard models including not only the on-site but also the inter-site Coulomb...
Incommensurate Mott Insulator in One-Dimensional Electron Systems close to Quarter Filling (2005)
Yoshioka, Hideo, Seo, Hitoshi, Fukuyama, Hidetoshi
A possibility of a metal-insulator transition in molecular conductors has been studied for systems composed of donor molecules and fully ionized anions with an incommensurate ratio close to 2:1 based...
Quantum Melting of Charge Order due to Frustration in Two-Dimensional Quarter-Filled Systems (2004)
Merino, Jaime, Seo, Hitoshi, Ogata, Masao
The effect of geometrical frustration in a two-dimensional 1/4-filled strongly correlated electron system is studied theoretically, motivated by layered organic molecular crystals. An extended...
Re-entrant Behavior and Gigantic Response in Disordered Spin-Peierls System (2004)
Seo, Hitoshi, Motome, Yukitoshi, Nagaosa, Naoto
Effects of disorder and external field on the competing spin-Peierls and antiferromagnetic states are studied theoretically in terms of the numerical transfer matrix method applied to a quasi...
Kuwabara, Makoto, Seo, Hitoshi, Ogata, Masao
The electronic properties of quarter-filled organic materials showing spin-Peierls transition are investigated theoretically. By studying the one-dimensional extended Peierls-Hubbard model...
One-Dimensional Confinement and Enhanced Jahn-Teller Instability in LaVO$_3$ (2002)
Motome, Yukitoshi, Seo, Hitoshi, Fang, Zhong, Nagaosa, Naoto
Ordering and quantum fluctuations of orbital degrees of freedom are studied theoretically for LaVO$_3$ in spin-C-type antiferromagnetic state. The effective Hamiltonian for the orbital pseudospin...
New aspects of Verway transition in magnetite (2001)
Seo, Hitoshi, Ogata, Masao, Fukuyama, Hidetoshi
A new mechanism of the Verway transition in magnetite (Fe3O4), which has been argued to be a charge ordering transition so far, is proposed. Based on the mean field calculations for the three band...
Charge Ordering in Organic ET Compounds (1999)
The charge ordering phenomena in quasi two-dimensional 1/4-filled organic compounds (ET)_2X (ET=BEDT-TTF) are investigated theoretically for the $\theta$ and $\alpha$-type structures, based on the...
Interplay between Structure and Electronic Properties in Organic Conductors (1999)
Fukuyama, Hidetoshi, Seo, Hitoshi, Kino, Hiori
It is known that the ground states of organic conductors have a diversity reflecting the spatial arrangement of the constituent molecules within the unit cell. A systematic theoretical search for the...
On the Spin Gap Phase in lambda-(BETS)_2GaX_zY_{4-z} (1998)
Seo, Hitoshi, Fukuyama, Hidetoshi
The nature of the insulating ground state in quasi-two-dimensional organic conductor lambda-(BETS)_2GaX_zY_{4-z}, where the existence of a spin gap is suggested by susceptibility measurement, has...
Charge Ordering and Spin gap in NaV_2O_5 (1998)
Seo, Hitoshi, Fukuyama, Hidetoshi
A possible ground state of NaV_2O_5 is proposed based on the Hartree approximation for both on-site and intersite Coulomb interactions. The results indicate that the intersite Coulomb interaction...
Frustrated Spin System in theta-(BEDT-TTF)_2RbZn(SCN)_4 (1998)
Seo, Hitoshi, Fukuyama, Hidetoshi
The origin of the spin gap behavior in the low-temperature dimerized phase of theta-(BEDT-TTF)_2RbZn(SCN)_4 has been theoretically studied based on the Hartree-Fock approximation for the on-site...
Antiferromagnetic Phases of One-Dimensional Quarter-Filled Organic Conductors (1997)
Seo, Hitoshi, Fukuyama, Hidetoshi
The magnetic structure of antiferromagnetically ordered phases of quasi-one-dimensional organic conductors is studied theoretically at absolute zero based on the mean field approximation to the...