Laplacian-Level Quantum Hydrodynamic Theory for Plasmonics

An accurate description of the optical response of subwavelength metallic particles and nanogap structures is a key problem of plasmonics. Quantum hydrodynamic theory (QHT) has emerged as a powerful method to calculate the optical response of metallic nanoparticles (NPs) since it takes into account...

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Autores principales:	Henrikh M. Baghramyan, Fabio Della Sala, Cristian Ciracì
Formato:	article
Lenguaje:	EN
Publicado:	American Physical Society 2021
Materias:	Physics QC1-999
Acceso en línea:	https://doaj.org/article/11c2dc5a3e13414eb75ea5b604d88bce
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spelling	oai:doaj.org-article:11c2dc5a3e13414eb75ea5b604d88bce2021-12-02T13:19:33ZLaplacian-Level Quantum Hydrodynamic Theory for Plasmonics10.1103/PhysRevX.11.0110492160-3308https://doaj.org/article/11c2dc5a3e13414eb75ea5b604d88bce2021-03-01T00:00:00Zhttp://doi.org/10.1103/PhysRevX.11.011049http://doi.org/10.1103/PhysRevX.11.011049https://doaj.org/toc/2160-3308An accurate description of the optical response of subwavelength metallic particles and nanogap structures is a key problem of plasmonics. Quantum hydrodynamic theory (QHT) has emerged as a powerful method to calculate the optical response of metallic nanoparticles (NPs) since it takes into account nonlocality and spill-out effects. Nevertheless, the absorption spectra of metallic NPs obtained with conventional QHT, i.e., incorporating Thomas-Fermi (TF) and von Weizsäcker (vW) kinetic energy (KE) contributions, can be affected by several spurious resonances at energies higher than the main localized surface plasmon (LSP). These peaks are not present in reference time-dependent density-functional-theory spectra, where, instead, only a broad shoulder exists. Moreover, we show here that these peaks incorrectly reduce the LSP peak intensity and have a strong dependence on the simulation domain size so that a proper calculation of QHT absorption spectra can be problematic. In this article, we introduce a more general QHT method accounting for KE contributions depending on the Laplacian of the electronic density (q), thus, beyond the gradient-only dependence of the TFvW functional. We show that employing a KE functional with a term proportional to q^{2} results in an absorption spectrum free of spurious peaks, with LSP resonance of correct intensity and numerically stable Bennett state. Finally, we present a novel Laplacian-level KE functional that is very accurate for the description of the optical properties of NPs of different sizes as well as for dimers. Thus, the Laplacian-level QHT represents a novel, efficient, and accurate platform to study plasmonic systems.Henrikh M. BaghramyanFabio Della SalaCristian CiracìAmerican Physical SocietyarticlePhysicsQC1-999ENPhysical Review X, Vol 11, Iss 1, p 011049 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Physics QC1-999
spellingShingle	Physics QC1-999 Henrikh M. Baghramyan Fabio Della Sala Cristian Ciracì Laplacian-Level Quantum Hydrodynamic Theory for Plasmonics
description	An accurate description of the optical response of subwavelength metallic particles and nanogap structures is a key problem of plasmonics. Quantum hydrodynamic theory (QHT) has emerged as a powerful method to calculate the optical response of metallic nanoparticles (NPs) since it takes into account nonlocality and spill-out effects. Nevertheless, the absorption spectra of metallic NPs obtained with conventional QHT, i.e., incorporating Thomas-Fermi (TF) and von Weizsäcker (vW) kinetic energy (KE) contributions, can be affected by several spurious resonances at energies higher than the main localized surface plasmon (LSP). These peaks are not present in reference time-dependent density-functional-theory spectra, where, instead, only a broad shoulder exists. Moreover, we show here that these peaks incorrectly reduce the LSP peak intensity and have a strong dependence on the simulation domain size so that a proper calculation of QHT absorption spectra can be problematic. In this article, we introduce a more general QHT method accounting for KE contributions depending on the Laplacian of the electronic density (q), thus, beyond the gradient-only dependence of the TFvW functional. We show that employing a KE functional with a term proportional to q^{2} results in an absorption spectrum free of spurious peaks, with LSP resonance of correct intensity and numerically stable Bennett state. Finally, we present a novel Laplacian-level KE functional that is very accurate for the description of the optical properties of NPs of different sizes as well as for dimers. Thus, the Laplacian-level QHT represents a novel, efficient, and accurate platform to study plasmonic systems.
format	article
author	Henrikh M. Baghramyan Fabio Della Sala Cristian Ciracì
author_facet	Henrikh M. Baghramyan Fabio Della Sala Cristian Ciracì
author_sort	Henrikh M. Baghramyan
title	Laplacian-Level Quantum Hydrodynamic Theory for Plasmonics
title_short	Laplacian-Level Quantum Hydrodynamic Theory for Plasmonics
title_full	Laplacian-Level Quantum Hydrodynamic Theory for Plasmonics
title_fullStr	Laplacian-Level Quantum Hydrodynamic Theory for Plasmonics
title_full_unstemmed	Laplacian-Level Quantum Hydrodynamic Theory for Plasmonics
title_sort	laplacian-level quantum hydrodynamic theory for plasmonics
publisher	American Physical Society
publishDate	2021
url	https://doaj.org/article/11c2dc5a3e13414eb75ea5b604d88bce
work_keys_str_mv	AT henrikhmbaghramyan laplacianlevelquantumhydrodynamictheoryforplasmonics AT fabiodellasala laplacianlevelquantumhydrodynamictheoryforplasmonics AT cristianciraci laplacianlevelquantumhydrodynamictheoryforplasmonics
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Laplacian-Level Quantum Hydrodynamic Theory for Plasmonics

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