The first 6-8 months of the project were spent mostly on the preliminary training for the background study of the quantum many body systems and the development of the analytical QHD model. We developed the QHD equations for a spherically symmetric system, applicable to hollow spherical molecules or nanoshells, e.g. fullerenes, gold nanoshells, etc. We first used the model for the description of plasmonic oscillations in the C60 fullerenes. C60 fullerenes exhibit collective plasmonic excitations against the positive ion background, associated with the localised surface plasmon (dipole) mode and the monopole plasmon (breathing) mode. These are attractive candidates for spectroscopic studies in understanding fundamental many-body physics. A variational technique was used to solve analytically the QHD model for the case of breathing plasmonic oscillations, revealing a resonantmode near the plasmon frequency (33 eV), slightly redshifted due to spillout effects, and a second mode around 19 eV.
By the end of 9 months of the project, we have acquired these results that were presented in some internal seminars, international workshops, summer school, etc. described below in details:
• Poster presentation: IPCMS days, 21 - 22 November 2016, CNRS-IPCMS, Strasbourg, France
• Poster presentation: EUCOR meeting on Quantum Science and Technology, 30 March 2017, Strasbourg, France
• Oral presentation: PhD students and Postdocs seminars, 2 June 2017, Department of ultrafast Optics and Nanophotonics (DON), CNRS-IPCMS, Strasbourg, France
• Poster presentation: 2nd International summer School in electronic structure Theory: electron correlation in Physics and Chemistry 18 June – 1 July, 2017, Centre Paul Langevin, Aussois (Savoie) France
On the basis of the knowledge acquired during the development of the QHD analytical method and results obtained for the ground state of the breathing mode of C60, the focus of the project was towards the numerical development of the QHD code. For that purpose, we first studied semi-analytically the linear and non-linear response of the C60 molecule. The computed bulk plasmon frequency is redshifted (both in linear and non-linear regimes) with respect to plasmon frequency due to the large spillout of the electron density with respect to the ion density. We further verified our obtained results from the QHD code by first-principles simulations based on a TDDFT approach. A second collective resonance was detected at 19 eV, same as the one observed in the QHD simulations, thus verifying our developed QHD code.
As a typical example, the QHD approach was used here to investigate the ground state and linear response of metallic nanoshells. Detailed comparison with a fully quantum TDDFT code revealed a satisfactory accordance between the two approaches. These results are encouraging for future more realistic studies of large nanoplasmonics structures using QHD.
Results presented (June 2017 – August 2018):
• Invited Seminar: 2 October 2017, Institut für Sensor- und Aktuatorsysteme, Micro and Nanosensors (MNS) Group, Technische Universität Wien, Vienna, Austria
• Oral presentation: Theory Days 2017, 22 – 24 November 2017, Toulouse, France
• Oral presentation: International Conference on Recent Advances on Mathematical and Physical Science [ICRAMPS 2018], Jhangirnagar University, Dhaka, Bangladesh, 27-29 January 2018
• Invited Seminar: 31 January 2018, Department of Physics, Bangladesh University of Engineering & Technology, Bangladesh.
• Invited Seminar: 1 June 2018, Dipartimento di Fisica "E. Pancini", Universita di Napoli “Federico II”, Napoli, Italy
• Poster presentation: Plasmonics and Nanophotonics Gordon Research Conference, 8 – 13 July 2018, Maine, USA
• Oral presentation: SPIE Nanoscience + Engineering 2018, 19 – 23 August 2018 San Diego, USA
