plasmonX: An open-source code for nanoplasmonics

We present the first public release of plasmonX , a novel open-source code for simulating the plasmonic response of complex nanostructures. The code supports both fully atomistic and implicit descriptions of nanomaterials. In particular, it employs the frequency-dependent fluctuating charges ( ω FQ) and dipoles ( ω FQF μ ) models to describe the response properties of atomistic structures, including simple and d -metals, graphene-based structures, and multi-metal nanostructures. For implicit representations, the Boundary Element Method is implemented in both the dielectric polarizable continuum model (DPCM) and integral equation formalism (IEF-PCM) variants. The distribution also includes a post-processing module that enables analysis of electric field-induced properties such as charge density and electric field patterns. PROGRAM SUMMARY Program Title: plasmonX CPC Library link to program files: https://doi.org/10.17632/zcd8fb4457.1 Developer’s repository link: https://github.com/plasmonX/plasmonX Licensing provisions: GPLv3 Programming language: Fortran 2008, Python Nature of problem: Simulating the response properties of plasmonic metallic and graphene-based nanomaterials. Solution method: Fully atomistic frequency-dependent fluctuating charges ( ω FQ) [1,2] and dipoles ( ω FQF μ ) [3] models and implicit, non-atomistic Boundary Element Methods (BEM) [4]. The approaches are implemented within the quasistatic approximation. Additional comments including restrictions and unusual features: The program has been mainly tested by using gfortran (versions 9-13) combined with the Math Kernel Library (MKL) provided by Intel. References [1] T. Giovannini, M. Rosa, S. Corni, C. Cappelli, A classical picture of subnanometer junctions: an atomistic Drude approach to nanoplasmonics, Nanoscale 11 (13) (2019) 6004–6015 [2] T. Giovannini, L. Bonatti, M. Polini, C. Cappelli, Graphene plasmonics: Fully atomistic approach for realistic structures, J. Phys. Chem. Lett. 11 (18) (2020) 7595–7602. [3] T. Giovannini, L. Bonatti, P. Lafiosca, L. Nicoli, M. Castagnola, P. G. Illobre, S. Corni, C. Cappelli, Do we really need quantum mechanics to describe plasmonic properties of metal nanostructures?, ACS Photonics 9 (9) (2022) 3025–3034. [4] F. J. García de Abajo, A. Howie, Retarded field calculation of electron energy loss in inhomogeneous dielectrics, Phys. Rev. B 65 (11) (2002) 115418.