arXiv subjects

Alessandro Toschi

Publications and source records attributed to Alessandro Toschi.

58 records · Page 4Linked to original sources

arXiv2012

Effective Onsite Interaction for Dynamical Mean-Field Theory

A scheme to incorporate non-local polarizations into the dynamical mean-field theory (DMFT) and a tailor-made way to determine the effective interaction for the DMFT are systematically investigated. Applying it to the two-dimensional Hubbard model, we find that non-local polarizations induce a non-trivial filling-dependent anti-screening effect for the effective interaction. The present scheme combined with density functional theory offers an ab initio way to derive effective onsite interactions for the impurity problem in DMFT. We apply it to SrVO3 and find that the anti-screening competes with the screening caused by the off-site interaction.

cond-mat.str-el↗

arXiv2011

Effects of electronic correlations and disorder on the thermopower of NaxCoO2

For the thermoelectric properties of NaxCoO2, we analyze the effect of local Coulomb interaction and (disordered) potential differences for Co-sites with adjacent Na-ion or vacancy. The disorder potential alone increases the resistivity and reduces the thermopower, while the Coulomb interaction alone leads only to minor changes compared to the one-particle picture of the local density approximation. Only combined, these two terms give rise to a substantial increase of the thermopower: the number of (quasi-)electrons around the Fermi level is much more suppressed than that of the (quasi-)holes. Hence, there is a particle-hole imbalance acting in the same direction as a similar imbalance for the group velocities. Together, this interplay results in a large positive thermopower. Introducing a thermoelectric spectral density, we located the energies and momenta regions most relevant for the thermopower and changes thereof.

cond-mat.str-el↗

arXiv2010

Wien2wannier: From linearized augmented plane waves to maximally localized Wannier functions

We present an implementaion of interface between the full-potential linearized augmented plane wave package Wien2k and the wannier90 code for the construction of maximally localized Wannier functions. The FORTRAN code and a documentation is made available and results are discussed for SrVO$_3$, Sr$_2$IrO$_4$ (including spin-orbit coupling), LaFeAsO, and FeSb$_2$.

cond-mat.mtrl-sci↗

arXiv2010

Dynamical vertex approximation for nanoscopic systems

With an increasing complexity of nanoscopic systems and the modeling thereof, new theoretical tools are needed for a reliable calculation of complex systems with strong electronic correlations. To this end, we propose a new approach based on the recently introduced dynamical vertex approximation. We demonstrate its reliability already on the one-particle vertex (i.e., dynamical mean field theory) level by comparison with the exact solution. Modeling a quantum point contact with 110 atoms, we show that the contact becomes insulating already before entering the tunneling regime due to a local Mott-Hubbard transition occurring on the atoms which form the point contact.

cond-mat.str-el↗