报告主题：A Different Perspective on Scattering Experiments Insights from Dynamical Mean Field Theory
报告人：Prof. Gheorghe Lucian Pascut
报告时间：2024-08-30 时间：9：00
报告地点：线上会议（腾讯会议号：358-328-389）

主办单位：物理与电子工程学院

报告摘要：

Correlated materials, defined by the strong coulomb interactions between electrons, are known to give rise to interesting physical properties such as metal to insulator transitions, ferroelectricity coexisting with long range magnetic order, orbital and charge ordering, etc. which are used to develop functionalities for electronic devices. The theoretical description of functionalities in correlated materials is very challenging, because the essential role is played by the electronic correlations, which are hard to account for in theoretical methods. In this respect, many theoretical methods for ab-initio description of strong electronic correlations in solids have been recently developed, and among them the Density Functional Theory (DFT) with Embedded Dynamical Mean Field Theory (eDMFT) was very successful. Theoretical description of the challenging electronic-structural interplay in the vicinity of a transition driven by electronic correlations, was only recently addressed due to the development of forces for structural relaxations within the DFT+eDMFT method. As a result of these developments, an advancement on the quantitative prediction of the basic bulk properties (crystal and magnetic structures, spectral functions, resonant X-ray scattering, etc.) of correlated materials is now possible. For the first time, the predictive power of the DFT+eDMFT method was demonstrated, by considering simultaneously structural and electronic degrees of freedom at finite temperatures on correlated materials such as NdNiO₃, Mn₂Mo₃O₈ and Fe₂Mo₃O₈, BiMnO₃ and LaMnO₃. At the same time, its predictive powers, were used to investigate the correlations phase diagram for LaNiO₂ and cooper-doped lead apatite, called LK-99. Besides quantitatively capturing the temperature dependence of both the electronic and structural properties, DFT+eDMFT method can predict the existence of novel electronic states of matter, with site or orbital selectivity, characterized by coexistence of insulating, semi-metallic and metallic orbitals, states that cannot be captured by other ab-initio methods such as DFT or its extensions, thus the DFT+eDMFT method is a powerful tool in the field of materials science due to its predictive powers. In this talk I will present results of literature review and theoretical results for some of the correlated materials mentioned above and I will try to convince you that synergy of experiments and the predictive power of the DFT+eDMFT method at finite temperatures can be used to guide experiments, design new experiments, explain and interpret the experimental results, thus allowing us to gain a deeper understanding of the correlated materials. Furthermore, employing the DFT+eDMFT method, I will introduce an alternative perspective on the concept of "charge disproportionation/order" in materials and argue that it is synonymous with the emergence of unique states of matter characterized by site or orbital selectivity.

报告人简介：

Gheorghe Lucian Pascut, Associate Professor. Department of Forestry, Stefan cel Mare University (USV), Suceava, Romania. He got Ph.D. in Physics, School of Physics, University of Bristol, United Kingdom.

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