Tokyo Institute of Technology · Materials Science
Professor Takehiko Mori's research lab specializes in the theoretical and computational investigation of electronic structures and electronic properties in organic conductors and superconductors, with a focus on the relationship between molecular packing, orbital overlap, and macroscopic electronic behavior. The lab employs extended Hückel molecular orbital calculations to analyze intermolecular interactions, particularly the overlap of highest occupied molecular orbitals (HOMOs), to understand band structures, Fermi surface topology, and the emergence of phenomena such as metal-insulator transitions and superconductivity. A central theme is the development of universal principles—such as the role of dihedral angles and lattice parameters—in explaining phase diagrams across various BEDT-TTF-based materials. The lab also explores magnetic interactions in π-d systems, contributing to the understanding of spin polarization and magnetic ordering in organic semiconductors.
Figures are computed from collected data and may differ slightly.
Abstract Based on the extended Hückel molecular orbital calculations, the relation between the anisotropy of the band structure and the arrangement of the organic molecules is investigated for two organic donors, tetrathiafulvalene (TTF) and bis(ethylenedithio)tetrathiafulvalene (BEDT–TTF). The intermolecular overlaps of their HOMO are calculated while the intermolecular arrangements are varied. The maps of the overlaps thus obtained are then used to estimate the band-structure parameters of (TM
Abstract Overlap integrals between HOMO’s of two non-parallel BEDT-TTF (bis(ethylenedithio)tetrathiafulvalene) molecules have been calculated. As the dihedral angle between the molecular planes decreases from 180° (parallel) to 90° (perpendicular), the overlap integral increases and attains a maximum around 90°. This accounts for the “universal phase diagram” of the θ-phase; θ-salts vary from an insulator to a metal with decreasing the dihedral angle. The ratio of the lattice constants in the co
Abstract A method is proposed to systematize a number of structural modifications of BEDT-TTF (bis(ethylenedithio)tetrathiafulvalene)-based organic conductors and related materials. Analysis of actual crystal structures indicates that most crystal structures are constructed of two essential building blocks: “ring-over-bond” (RB) and “ring-over-atom” (RA) overlap modes. Several different ways to pile up these elements lead to various structures which are conventionally designated as β,β′,β″,θ,α,
Abstract On the basis of the extended Hückel molecular orbital calculation, the intermolecular overlaps of the highest occupied molecular orbitals are calculated for α-(BEDT-TTF)2I3 reported by Bender et al., and for superconducting β-(BEDT-TTF)2I3 reported by Yagubskii et al. (BEDT-TTF: bis(ethylenedithio)tetrathiafulvalene). α-(BEDT-TTF)2I3 is a two-dimensional semimetal or a narrow gap semiconductor. β-(BEDT-TTF)2I3 is a two-dimensional metal which has an almost isotropic closed Fermi surface
Magnetic interactions in organic conductors including magnetic anions, such as λ-(BETS) 2 FeCl 4 and κ-(BETS) 2 FeX 4 [X = Cl and Br], are estimated from intermolecular overlap integrals; the overlaps between anions afford J dd , and those between anions and donors give J πd . From this, the most stable spin alignments are decided, and such quantities as the Néel and Weiss temperatures, as well as the magnitude of spin polarization on the π-molecules are evaluated on the basis of the mean-field
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOrganic Conductors with Unusual Band FillingsTakehiko MoriView Author Information Department of Organic and Polymeric Materials, Tokyo Institute of Technology, O-okayama 2-12-1, Meguro-ku, Tokyo 152-8552, Japan Cite this: Chem. Rev. 2004, 104, 11, 4947–4970Publication Date (Web):July 28, 2004Publication History Received5 February 2004Published online28 July 2004Published inissue 1 November 2004https://pubs.acs.org/doi/10.1021/cr030660xhttps://doi.org/1
Below 4 K the [Au(CN)2] salt of the radical cation of 1 shows superconductivity. The X-ray structure analysis reveals that this salt has a two-dimensional array of donors. The relatively large interactions between the stacks result in a closed Fermi surface.
A new family of organic molecules, 2-${R}_{1}$-5-${R}_{2}$-DCNQI (with ${R}_{1}$,${R}_{2}$=${\mathrm{CH}}_{3}$, ${\mathrm{CH}}_{3}$O, Cl, or Br; DCNQI=N,N'-dicyanoquinonediimine) works as a ligand as well as an electron acceptor to form highly conducting, charge-transfer and coordination compounds as (2-${R}_{1}$-5-${R}_{2}$-DCNQI${)}_{2}$M (with M=Cu, Ag, Li, Na, K, or ${\mathrm{NH}}_{4}$). These salts are investigated by the measurements of electrical conductivity, thermoelectric power, and el
Abstract δ-phase (β-PF6 type) BEDT-TTF (bis(ethylenedithio)tetrathiafulvalene)-based organic conductors are characterized by the twisted overlap mode in the stack. Since the twisted mode has large intermolecular orbital overlap, the δ-phase is regarded as a twisted dimer structure. This type of overlap is, however, insensitive to small changes of the structure. On the contrary, an oblique interaction alters the warping of the open Fermi surface, to control the metal-insulator transition temperat
Abstract In recent years, several bounds have been reported for different measures of the ‘ extent’ or ‘ size ’ of the solution of the algebraic matrix equations arising in control theory, such as the Riccati equation and the Lyapunov equation. This paper collects the bounds that have been presented up to now and summarizes them in an unified form. This will prove particularly convenient for those wishing to get a ready estimate of the solution while solving the equations numerically or to devel
Phase diagrams of charge order patterns of the θ-phase organic conductors are investigated on the basis of the static-limit extended Hubbard model including the second nearest Coulomb repulsion V '. Since the θ-phase is close to the triangular lattice rather than the square lattice, a 3-fold non-stripe charge order is stable in a considerably large region between the stripe phases and the uniform phase. At finite temperatures, such unevenly ordered patterns as the 3-fold phase D + D 2 1/4+ becom
We report the quantitative evaluation of the UV scattering effect on the SO 2 emission rate measurement by the compact UV spectrometer system. Plume spectra were obtained simultaneously at three measuring points with different distance to the volcanic plume. The apparent absorbance decreases with increasing distance to the plume and the attenuation becomes stronger at shorter wavelength bands. In addition, the attenuation intensity depends on the SO 2 column concentration. The underestimation of
A bio-inspired organic semiconductor 5,5′-diphenylindigo shows excellent and well-balanced ambipolar transistor properties; its hole and electron mobilities are 0.56 and 0.95 cm2 V−1 s−1, respectively. The enhanced performance is attributed to the extended π–π overlap of the phenyl groups as well as the characteristic packing pattern that is a hybrid of the herringbone and brickwork structures. The ambipolar transistor characteristics are analyzed considering its operating regions, where a large
Abstract Intermolecular Coulomb repulsion, V, of the highest occupied molecular orbitals (HOMO) of BEDT-TTF (bis(ethylenedithio)tetrathiafulvalene) is calculated for various molecular geometries. The bare V is a quantity that is easily estimated under the point charge approximation. As far as the screened V in actual crystals is proportional to the calculated bare V, the usual θ-phase prefers the horizontal or diagonal stripe, whereas the vertical stripe becomes comparatively stable in the limit
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