Harvard University

腾讯会议ID:  768-598-092

会议密码：1218 

Abstract：

Current materials simulation faces computational limitations, prompting a keen interest in large-scale Density Functional Theory (DFT) algorithms. We have developed three distinct methods—ML-TB, charge density patching, and optimized atomic orbital DFT—each capable of computing the electronic structure of materials containing up to 100,000 atoms. Employing these advanced self-consistent calculations, we explored the electronic and optical properties of twisted bilayer systems and the possible applications in devices, without relying on any free parameters. Our investigations revealed artificial-atom states and quantum-dot arrays in twisted PbS, and we extended the computation of twistronics beyond van der Waals (vdW) materials, marking the first instance of a twisted structure non-vdW materials. Leveraging the localized and well-arranged states near the Fermi level in real space, we innovatively designed a new class of scalable qubits. Additionally, we delved into the geometry of 3D moir superlattices, unveiling potential properties such as a novel nonlinear Hall effect, nontrivial magnetism, and unique optical selection rules (e.g., chiral selection) in various twisted materials.

Utilizing Time-Dependent Density Functional Theory (TDDFT) simulations, we probed coherent electron-phonon coupling and electron dynamics in Dirac materials, for example Rb2Mo6S6. Furthermore, employing an analytical Hamiltonian, we unveiled a Floquet crystal driven by electron-phonon interaction in this context. Our exploration of superconductors discovered some characteristic phonon modes, which are predominant. The electrons are nonadiabatically excited by phonons, leading to coherent electron-hole density wave. The frequency of these modes shows correlation with the corresponding superconductivity transition temperature.

Brief CV of Dr. Zhigang Song:

宋志刚，哈弗大学博士后。2012年本科毕业于郑州大学物理系，2017年获北京大学大学博士学位，导师杨金波和吕劲。2015-2016 年在麻省理工大学材料学院交流访问，导师李巨。2018-2021 美国加州大学伯克利分校和劳伦斯国家实验室开展博士后研究，导师汪林望。 2021年至今在美国哈弗大学开展博士后研究工作，导师Prienha Narang。至今，发表论文70余篇，被引用大约2800次（google scholar）。以第一/共同第一/通讯作者身份在Science, JACS, Phys. Rev. Lett., Science advances, Advanced materials, Nano letters, ACS nano等期刊发表论文10余篇。2023 以重要作者获得美国能源部R&D 100 大奖。

主  持  人：成昭华   研究员

联  系  人：傅    琦（82649469）