Electronic Correlations in Vanadium Revealed by Electron-Positron Annihilation Measurements

The electronic structure of vanadium measured by Angular Correlation of electron-positron Annihilation Radiation (ACAR) is compared with the predictions of the combined Density Functional and Dynamical Mean-Field Theory (DMFT). Reconstructing the momentum density from five 2D projections we were able to determine the full Fermi surface and found excellent agreement with the DMFT calculations. In particular, we show that the local, dynamic self-energy corrections contribute to the anisotropy of the momentum density and need to be included to explain the experimental results

On the superconducting nature of the Bi-II phase of elemental Bismuth

The superconductivity in the Bi-II phase of elemental Bismuth (transition temperature $T_{\rm c}\simeq3.92$ K at pressure $p\simeq 2.80$ GPa) was studied experimentally by means of the muon-spin rotation as well as theoretically by using the Eliashberg theory in combination with Density Functional Theory calculations. Experiments reveal that Bi-II is a type-I superconductor with a zero temperature value of the thermodynamic critical field $B_{\rm c}(0)\simeq31.97$~mT. The Eliashberg theory approach provides a good agreement with the experimental $T_{\rm c}$ and the temperature evolution of $B_{\rm c}$. The estimated value for the retardation (coupling) parameter $k_{\rm B}T_{\rm c}/\omega_{\rm ln} \approx 0.07$ ($\omega_{\rm ln}$ is the logarithmically averaged phonon frequency) suggests that Bi-II is an intermediately-coupled superconductor.Comment: 6 pages, 2 figure

Abstracts from the 20th International Symposium on Signal Transduction at the Blood-Brain Barriers

https://deepblue.lib.umich.edu/bitstream/2027.42/138963/1/12987_2017_Article_71.pd

Realistic Modelling of Correlated Metals within Dynamical Mean-Field Theory

In this study we present results of electronic structure calculations for metals, based on density functional theory and its combination with dynamical mean-field theory. The scattering amplitude of X-rays on electrons in metals, the so called Compton profile, is modeled. In particular we investigate the Compton profile for Alkali metals, and transition metal elements Copper, Gold and Silver. In the regime of high momentum transfer a certain scaling behavior of the Compton profiles is found. The influence of strong electron-electron interactions on the Compton profile is analyzed along nearest and next-nearest bonding directions for the $3d$-transition metal elements, iron and nickel. The results show a redistribution of the spectral weight in the Compton profile towards lower momenta. The effects of electronic correlation were also studied in palladium using a realistic multi-orbital Hubbard model. A better agreement with the experimental lattice constant and bulk modulus is obtained when electronic correlations are included. Small changes in the Fermi surface were found in agreement with experiments and other theroretical studies, where non-local correlation effects were included in the description. A satellite formation in the high energy binding region of the spectral function can be reproduced employing dynamical mean-field theory. In addition, we investigated the lattice dynamics of palladium in the presence of electron correlation. A better agreement is found with experimentally obtained phonon spectra

Realistic Modelling of Correlated Metals within Dynamical Mean-Field Theory

In this study we present results of electronic structure calculations for metals, based on density functional theory and its combination with dynamical mean-field theory. The scattering amplitude of X-rays on electrons in metals, the so called Compton profile, is modeled. In particular we investigate the Compton profile for Alkali metals, and transition metal elements Copper, Gold and Silver. In the regime of high momentum transfer a certain scaling behavior of the Compton profiles is found. The influence of strong electron-electron interactions on the Compton profile is analyzed along nearest and next-nearest bonding directions for the $3d$-transition metal elements, iron and nickel. The results show a redistribution of the spectral weight in the Compton profile towards lower momenta. The effects of electronic correlation were also studied in palladium using a realistic multi-orbital Hubbard model. A better agreement with the experimental lattice constant and bulk modulus is obtained when electronic correlations are included. Small changes in the Fermi surface were found in agreement with experiments and other theroretical studies, where non-local correlation effects were included in the description. A satellite formation in the high energy binding region of the spectral function can be reproduced employing dynamical mean-field theory. In addition, we investigated the lattice dynamics of palladium in the presence of electron correlation. A better agreement is found with experimentally obtained phonon spectra

Realistic Modelling of Correlated Metals within Dynamical Mean-Field Theory

In this study we present results of electronic structure calculations for metals, based on density functional theory and its combination with dynamical mean-field theory. The scattering amplitude of X-rays on electrons in metals, the so called Compton profile, is modeled. In particular we investigate the Compton profile for Alkali metals, and transition metal elements Copper, Gold and Silver. In the regime of high momentum transfer a certain scaling behavior of the Compton profiles is found. The influence of strong electron-electron interactions on the Compton profile is analyzed along nearest and next-nearest bonding directions for the $3d$-transition metal elements, iron and nickel. The results show a redistribution of the spectral weight in the Compton profile towards lower momenta. The effects of electronic correlation were also studied in palladium using a realistic multi-orbital Hubbard model. A better agreement with the experimental lattice constant and bulk modulus is obtained when electronic correlations are included. Small changes in the Fermi surface were found in agreement with experiments and other theroretical studies, where non-local correlation effects were included in the description. A satellite formation in the high energy binding region of the spectral function can be reproduced employing dynamical mean-field theory. In addition, we investigated the lattice dynamics of palladium in the presence of electron correlation. A better agreement is found with experimentally obtained phonon spectra