B.S., 1968, Seoul National University M.S., 1970, Seoul National University Ph.D., Queen's University, Canada Postdoctoral Fellow, 1975-76, Queen's University, Canada Postdoctoral Associate, 1976-77, Cornell University

Inorganic and Computational Chemistry

At Present my research efforts are focused on the following topics:

(1) Electronic Band Structures of Low-Dimensional Metallic Compounds In understanding the transport and other physical properties of low-dimensional metallic compounds, it is essential to know how their electronic structures are related to their crystal structures. In this project we attempt to provide theoretical understanding for transport, optical and structural properties of various low-dimensional conducting materials, which include transition-metal compounds and organic conducting salts. To achieve this objective, we carry out electronic band structure, density of state and Fermi surface calculations. To probe the structure-property relationships governing these compounds, the calculated electronic structures of these compounds are analyzed from the viewpoint of chemical concepts such as orbital interaction, overlap and symmetry.

(2) Theoretical Study of Spin Exchange Interactions in Magnetic Solids Physical properties of a magnetic solid are described by a spin-Hamiltonian, which is written in terms of pair-wise spin exchange interactions and the associated spin exchange parameters. When the magnetic susceptibility, neutron inelastic scattering or Raman scattering data of a magnetic solid are analyzed in terms of a spin-Hamiltonian, the spin exchange parameters are obtained as numerical fitting parameters needed to reproduce the experimental data. This project attempts to correlate such “experimental” parameters with the geometrical structure of a magnetic solid by performing electronic structure calculations for its spin dimers (i.e., the structural units containing two adjacent spin sites). In this project, the spin exchange parameters of a magnetic solid are determined using first principles electronic structure calculations. In addition, the trends in the spin exchange parameters of magnetic solids are explained on the basis of semi-empirical electronic structure calculations.

M.-H. Whangbo and H.-J. Koo, "Spin dimer analysis of the spin exchange interactions in paramelaconite Cu4O3 and its analogue Ag2Cu2O3 and the spin ordering of the Cu2O3 spin lattice leading to their magnetic phase transitions", Inorg. Chem., 41 , 3570-3577 (2002). H.-J. Koo, M.-H. Whangbo, P. D. VerNooy, C. C. Torardi and W. J. Marshall, "Flux growth of vanadyl pyrophosphate (VO)2P2O7 and spin dimer analysis of the spin change interactions of (VO)2P2O7 and vanadyl hydrogen phosphate VO(HPO4)•0.5H2O", Inorg. Chem., 41, 4664-4672 (2002). M.-H. Whangbo, H.-J. Koo, D. Dai and D. Jung, "Importance of bond lengths on the strengths of metal-ligand-metal superexchange interactions: spin dimer analysis of the magnetic structure of marokite CaMn2O4", Inorg. Chem., 41, 5575-5581 (2002). H.-J. Koo, M.-H. Whangbo and K.-S. Lee, "Spin dimer analysis of the three-dimensional antiferromagnetic ordering in the quaternary manganese sulfides BaLn2MnS5 (Ln = La, Ce, Pr)", J. Solid State Chem., 169, 143-148 (2002). D. Dai and M.-H. Whangbo, "Spin Exchange Interactions of a Spin Dimer: Analysis of Broken-Symmetry Spin States in Terms of the Eigenstates of Heisenberg and Ising Spin Hamiltonians", J. Chem. Phys., 118, 29 (2003). M.-H. Whangbo, D. Dai and H.-J. Koo and S. Jobic, "Investigations of the oxidation states and spin distributions in Ca3Co2O6 and Ca3CoRhO6 by spin-polarized electronic band structure calculations", Solid State Commun., 125, 413 (2003). H.-J. Koo and M.-H. Whangbo, "Magnetic superstructures of cupric oxide CuO as ordered arrangements of one-dimensional antiferromagnetic chains", Inorg. Chem., 42, 1187-1192 (2003). D. Dai, H.-J. Koo, M.-H. Whangbo, C. Soulard, X. Rocquefelte and S. Jobic, "Trends in the structure and bonding in the layered platinum dioxide and dichalcogenides PtQ2 (Q = O, S, Se, Te)", J. Solid State Chem., 173, 114-121 (2003). M.-H. Whangbo, H.-J. Koo, D. Dai and D. Jung, "Need to assess the relative strengths of spin exchange interactions on the basis of electronic structure considerations. Importance of super-superexchange interactions involving Cu2+ ions in Cu2Te2O5X2 (X = Cl, Br) and Ca3.1Cu0.9RuO6", Inorg. Chem., 42, 3898-3906 (2003). J. Etourneau, A. Ammar, A. Villesuzanne, G. Villeneuve, B. Chevalier, M.-H. Whangbo, "Unusual hysteresis in the magnetic susceptibility of cubic hexaboride KB6", Inorg. Chem., 42, 4242-4244 (2003).

M.-H. Whangbo, H.-J. Koo and D. Dai, "Spin exchange interactions and magnetic structures of extended magnetic solids with localized spins: Theoretical descriptions on formal, quantitative and qualitative levels", J. Solid State Chem., in press.