亿万先生MR

沪上量子大讲堂-基于第一性道理的超导临界温度预测

2025.04.28

投稿:严巧赟部门:科研治理部浏览次数:

活动信息

汇报标题 (Title):How to predict the critical temperature of superconductors: an ab-initio perspective (基于第一性道理的超导临界温度预测)

汇报人 (Speaker):E. K. U. Gross (Fritz-Haber Center for Molecular Dynamics, The Hebrew University of Jerusalem)

汇报功夫 (Time):2025年5月13日(星期二) 15:00-16:30

汇报地址 (Place):宝山校区 乐乎新楼 学海厅

主办部门:量子科技钻研院、科研治理部高档钻研院

主持人:钟建新教授

汇报人简介:

Eberhard K. U. Gross教授是含时密度泛函理论(TDDFT)的奠基人。他与Erich Runge一路证了然驰名的Runge-Gross定理,为TDDFT奠定了数学基础。此表,他是将线性响应TDDFT用于推算分子光谱的先驱,还将实时TDDFT利用于超快电子动力学的推算,在理论上首先预言了磁性资猜中光诱导的自旋转移景象,并很快被尝试证实。在资料推算方面,他进一步发展了用于引发态推算的系综DFT理论,以及声子驱动超导的第一性道理步骤。近年来,他发展了针对原子核-电子系统的严格分化(exact factorization)步骤,用于描述非绝热动力学的各类景象,出格是涉及电子退有关以及分子几何相位效应的具体过程。

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汇报提要:

A prominent challenge of modern condensed-matter theory is to predict material-specific properties of superconductors, such as thecritical temperature. The traditional model of Bardeen, Cooper and Schrieffer (BCS) properly describes the universal features which all conventional superconductors have in common, but it is not able to make predictions of acceptable accuracy for material-specific properties. To tackle this problem, a density-functional-type theory will be presented. In this approach, the electron-phonon interaction and the electron-electron repulsion are treated on the same footing. There are no adjustable parameters suchas the μ*of Eliashberg theory. Approximations of the universal exchange-correlation functional are derived on the basis of many-body perturbation theory [1]. The predictive power of the method is demonstrated for a variety of phonon-mediated superconductors, including elemental hydrogen and hydrides under extreme pressure, as well as multigap superconductors like MgB2and Pb. Materials such as NbSe2, featuring a complicated competition between superconductivity and a charge density wave at low temperature,can be fully understood [2]. The superconducting order parameter in real space is an output of our ab-initio theory. It turns out that the order parameter essentially “lives” in the chemical bonds, i.e., is largest within the bonds [3]. For the class of MgB2–type superconductors, we demonstrate that the degree of localization of the sigma bonds correlates with the critical temperature of the material.Routes to locally tailoring [4] the order parameter will be discussed.

[1] A Sanna, C Pellegrini, EKU Gross, PRL125, 057001 (2020).

[2] A Sanna, C Pellegrini, E Liebhaber, K Rossnagel, KJ Franke, EKU Gross, npj Quant Materials7:6(2022)

[3] A Linscheid, A Sanna, A Floris, EKU Gross, PRL115, 097002 (2015).

[4] M Schackert, T M?rkl, J Jandke, M H?lzer, S Ostanin, EKU Gross, A Ernst, W Wulfhekel, PRL114, 047002 (2015).

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