Surface-response functions are one of the most promising routes for bridging the gap between fully quantum-mechanical calculations and phenomenological models in quantum nanoplasmonics. Within all the currently available recipes for obtaining such response functions, \emph{ab initio} calculations remain one of the most predominant, wherein the surface-response function are retrieved via the metal's non-equilibrium response to an external perturbation. Here, we present a complementary approach where one of the most appealing surface-response functions, namely the Feibelman $d$-parameters, yield a finite contribution even in the case where they are calculated directly from the equilibrium properties described under the local-response approximation (LRA), but with a spatially varying equilibrium electron density. Using model calculations that mimic both spill-in and spill-out of the equilibrium electron density, we show that the obtained $d$-parameters are in qualitative agreement with more elaborate, but also more computationally demanding, \emph{ab initio} methods. The analytical work presented here illustrates how microscopic surface-response functions can emerge out of entirely local electrodynamic considerations.
Local-field effects in current transport through molecular electronic devices: Current density profiles and local non-equilibrium electron distributions
Response to ``Comment on `time-dependent density-matrix renormalization group: a systematic method for the study of quantum many-body out-of-equilibrium systems''' by H. G. Luo, T. Xiang, and X. Q. Wang
Kinetics of 2D electrons in the magnetic field in the presence of microwave radiation. Response of a non-equilibrium system to a weak measurement field
Can out-of-equilibrium linear response reveal anyonic statistics?
National Laboratory of Solid State Microstructures, School of Physics, Jiangsu Physical Science Research Center and Collaborative Innovation Center of Advanced Microstructures, Nanjing University（南京大学固体微结构物理国家重点实验室、物理学院、江苏物理科学与技术研究中心和先进微结构协同创新中心）；Beijing Academy of Quantum Information Sciences（北京量子信息科学研究院）；Institute for Quantum Materials and Technologies and Institut für Theorie der Kondensierten Materie, Karlsruhe Institute of Technology（卡尔斯鲁厄理工学院量子材料与技术研究所及凝聚态理论研究所）；Department of Condensed Matter Physics, Weizmann Institute of Science（魏茨曼科学研究所凝聚态物理系）
