| N. A. Bogdanov(1), H.-Y. Huang(1,2), P. Fulde(3,4), J. van den Brink(1), and L. Hozoi(1) (1) Institute for Theoretical Solid State Physics, IFW Dresden, Germany (2) Synchrotron Light Source and National Tsing Hua University, Hsinchu, Taiwan (3) Max-Planck-Institut für Physik komplexer Systeme, Dresden, Germany (4) POSTECH, San 31 Hyoja-dong, Namgu Pohang, Gyeongbuk, Korea We use an embedding scheme based on solid-state periodic Hartree-Fock calculations for subsequent embedded-cluster MCSCF and MRCI investigations of the correlated d-level electronic structure of a variety of transition metal oxides [1-3]. Results for the d-level splittings are compared with resonant inelastic x-ray scattering (RIXS) experiments, which have recently emerged as a most powerful tool to reliably probe the charge, spin, and orbital degrees of freedom of correlated electrons in solids [4,5]. A complete set of local excitations has been computed for 1D and 2D Cu oxides and excellent agreement was found with RIXS [2]. We stress it is important to properly describe the charge distribution at metal and ligand sites next to the active octahedron for which local excitations are explicitly computed. On low-dimensional oxychlorides such as TiOCl and VOCl our study [3] shows that orbital degeneracies are lifted to a similar and significant extent, which excludes the presence of strong orbital fluctuations in the ground-state configuration as earlier suggested on the basis of mean-field DFT calculations. For 5d S = 3/2 systems such as Cd2Os2O7 and NaOsO3, we investigate the interplay of electron correlations, spin-orbit couplings, and lattice distortion effects. In particular, we predict large superexchange interactions of few dozen meV and analyze the zero-field splittings and Dzyaloshinsky-Moriya terms in the spin Hamiltonians. We convincingly demonstrate that in strongly correlated solid-state electronic systems, wave-function techniques provide essential information which otherwise cannot be accessed by DFT or extensions of DFT such as LDA+U and LDA+DMFT. [1] L. Hozoi, U. Birkenheuer, H. Stoll, P. Fulde, New J. Phys. 11, 023023 (2009). [2] H.-Y. Huang, N. A. Bogdanov, L. Siurakshina, P. Fulde, J. van den Brink, L. Hozoi, Phys. Rev. B 84, 235125 (2011). [3] N. A. Bogdanov, J. van den Brink, L. Hozoi, Phys. Rev. B 84, 235146 (2011). [4] L. Ament, M. van Veenendaal, T. Devereaux, J. Hill, J. van den Brink, Rev. Mod. Phys. 83, 705 (2011). [5] J. Schlappa, K.Wohlfeld, K. J. Zhou, M. Mourigal, M. W. Haverkort, V. N. Strocov, L. Hozoi, C. Monney, S. Nishimoto, S. Singh, A. Revcolevschi, J.-S. Caux, L. Patthey, H. M. Rønnow, J. van den Brink, T. Schmitt, Nature 485, 82 (2012). |
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