In: Proceedings of the National Academy of Sciences, 2020, vol. 117, no. 12, p. 6409-6416
The role of the crystal lattice for the electronic properties of cuprates and other high-temperature superconductors remains controversial despite decades of theoretical and experimental efforts. While the paradigm of strong electronic correlations suggests a purely electronic mechanism behind the insulator-to-metal transition, recently the mutual enhancement of the electron–electron and the...
|
In: Physical Review B, 2018, vol. 97, no. 12, p. 125149
Recent ultrafast magnetic-sensitive measurements [Johnson et al., Phys. Rev. B 92, 184429 (2015); Bothschafter et al., Phys. Rev. B 96, 184414 (2017)] have revealed a delayed melting of the long-range cycloid spin order in TbMnO3 following photoexcitation across the fundamental Mott-Hubbard gap. The microscopic mechanism behind this slow transfer of energy from the photoexcited carriers to...
|
In: Physical Review B, 2013, vol. 87, no. 12, p. 125149
We describe a recent implementation of the combined GW and dynamical mean field method (GW+DMFT) for the two-dimensional Hubbard model with onsite and nearest-neighbor repulsion. We clarify the relation of the GW+DMFT scheme to alternative approaches in the literature, and discuss the corresponding approximations to the free-energy functional of the model. Furthermore, we describe a numerically...
|
In: Physical Review Letters, 2012, vol. 109, no. 22, p. 226401
We present a fully self-consistent combined GW and dynamical mean field (DMFT) study of the extended two-dimensional Hubbard model. The inclusion of the local dynamical vertex stemming from the DMFT self-energy and polarization is shown to cure the known problems of self-consistent GW. We calculate momentum-resolved spectral functions, two-particle polarizations, and electron-loss spectra, as...
|
In: Inorganic Chemistry, 2011, vol. 50, no. 16, p. 7460–7477
A theoretical, computational, and conceptual framework for the interpretation and prediction of the magnetic anisotropy of transition metal complexes with orbitally degenerate or orbitally nearly degenerate ground states is explored. The treatment is based on complete active space self-consistent field (CASSCF) wave functions in conjunction with N-electron valence perturbation theory...
|
In: Physical Review Letters, 2009, vol. 102, no. 13, p. 130603
We study the unitary time evolution of antiferromagnetic order in anisotropic Heisenberg chains that are initially prepared in a pure quantum state far from equilibrium. Our analysis indicates that the antiferromagnetic order imprinted in the initial state vanishes exponentially. Depending on the anisotropy parameter, oscillatory or nonoscillatory relaxation dynamics is observed. Furthermore, the...
|
In: The Journal of Physical Chemistry A, 2007, vol. 111, no. 37, p. 9145 -9163
The topology of the ground-state potential energy surface of M(CN)₆ with orbitally degenerate ²T2g (M = TiIII (t2g¹), FeIII and MnII (both low-spin t2g⁵)) and ³T1g ground states (M = VIII (t2g²), MnIII and CrII (both low-spin t2g⁴)) has been studied...
|
In: The Journal of Physical Chemistry A, 2006, vol. 110, no. 49, p. 13332 -13340
Exchange coupling across the cyanide bridge in a series of novel cyanometalate complexes with CuII-NC-MIII (M = Cr and low-spin Mn,Fe) fragments has been studied using the broken-symmetry DFT approach and an empirical model, which allows us to relate the exchange coupling constant with σ-, π-, and π*-type spin densities of the CN⁻ bridging ligand. Ferromagnetic...
|
In: Physica Status Solidi b, 2007, vol. 244, no. 7, p. 2299 - 2303
A refined variational wave function for the two-dimensional repulsive Hubbard model is studied numerically, with the aim of approaching the difficult crossover regime of intermediate values of U. The issue of a superconducting ground state with d-wave symmetry is investigated for an average electron density n≈ 0.8 and for U = 8t. Due to finite-size effects a...
|
In: Comptes Rendus Chimie, 2005, vol. 8(9-10), p. 1421-1433
An overview of the theory and applications of a recently proposed ligand-field density functional theory (LFDFT) is given. We describe a procedure based on DFT allowing to deduce the parameters of this non-empirical LF approach consisting of the following steps: (i) an average of configuration (AOC) DFT calculation, with equal occupancies of the d-orbitals is carried out (ii) with...
|