题目：Exploration of complex materials using advanced computational methods

报告人：张瑞奇

邀请人：林海青

时间：2024年10月17日（周四）10:00

地点：紫金港校区海纳苑8幢215报告厅

摘要：

Complex materials often consisting of d- and f-electrons, such as heavy-Fermion compounds and high-Tc superconductors, have drawn intensive interest for their potential applications in material and quantum information science and their scientific significance. However, accurately modeling these materials has been a challenge. Therefore, developing advanced computational methods plays a critical role in materials science, chemistry, and condensed matter physics by providing valuable insights into the underlying physics and properties of novel materials. In the first part of this discussion, I will show the importance of the strongly-constrained and appropriately-normed (SCAN) functional with symmetry breaking in advancing the theoretical treatment of highly correlated materials. Specifically, I will share our insights on the puzzles of the heavy-fermion compound SmB6, including its highly debated quantum oscillations. Additionally, I will present our recent calculations, which demonstrate that the undoped LaNiO2––a newly discovered superconductor–– hosting competing low-energy stripe phases is similar to doped cuprates. In the second part, I will show how allowing for non-integer nuclear charges expands the space of computationally tractable electron systems hosting competing electronic states. The simple 2-electron H2 molecule exemplifies this by showing the competition between charge transfer and strong correlations. Additionally, the emergence of competing electronic states in doped quasi-1D cuprate chains was demonstrated using this approach. Our findings show how non-integer nuclear charges can open a window for first-principles calculations of difficult many-electron phenomena.

个人简介：

Dr. Ruiqi Zhang completed his Ph.D. in 2018 under the guidance of Prof. Jinlong Yang at the University of Science and Technology of China. He stated his postdoc appointment from 2018 at Tulane University and was promoted to research assistant professor in 2023. His recent focus involves investigating the electronic structures of strongly correlated materials like cuprates and nickelates, utilizing advanced density functional theory (DFT) with symmetry-breaking and Hamiltonian model calculations. His significant contributions in this field have led to an invitation to deliver an invited talk at the 2024 APS March Meeting.