Electron correlation and spin-orbit coupling effects in US3 and USe3

A systematic density functional theory (DFT)+U study is conducted to investigate the electron correlation and spin-orbit coupling (SOC) effects in US3 and USe3. Our calculations reveal that inclusion of the U term is essential to get energy band gaps for them, indicating the strong correlation effects for uranium 5f electrons. Taking consideration of the SOC effect results in small reduction on the electronic band gaps of US3 and USe3, but largely changes the energy band shapes around the Fermi energy. As a result, US3 has a direct band gap while USe3 has an indirect one. Our calculations predict that both US3 and USe3 are antiferromagnetic insulators, in agreement with corresponding experimental results. Based on our DFT+U calculations, we systematically present the ground-state electronic, mechanical, and Raman properties for US3 and USe3.Comment: 6 pages, 6 figure

Electrical and optical properties of fluid iron from compressed to expanded regime

Using quantum molecular dynamics simulations, we show that the electrical and optical properties of fluid iron change drastically from compressed to expanded regime. The simulation results reproduce the main trends of the electrical resistivity along isochores and are found to be in good agreement with experimental data. The transition of expanded fluid iron into a nonmetallic state takes place close to the density at which the constant volume derivative of the electrical resistivity on internal energy becomes negative. The study of the optical conductivity, absorption coefficient, and Rosseland mean opacity shows that, quantum molecular dynamics combined with the Kubo-Greenwood formulation provides a powerful tool to calculate and benchmark the electrical and optical properties of iron from expanded fluid to warm dense region