A first-principles study of the influence of helium atoms on the optical response of small silver clusters
Optical excitation spectra of Agn and Agn@He60 (n = 2, 8) clusters are investigated in the framework of the time-dependent density functional theory (TDDFT) within the linear response regime. We have performed the ab initio calculations for two different exact exchange functionals (GGAexact and LDA-exact). The computed spectra of Agn@He60 clusters with the GGA-exact functional accounting for exchange-correlation effects are found to be generally in a relatively good agreement with the experiment. A strategy is proposed to obtain the ground-state structures of the Agn@He60 clusters and in the initial rocess of the geometry optimization, the He environment is simulated with buckyballs. A redshift of the silver clusters spectra is observed in the He environment with respect to the ones of bare silver clusters. This observation is discussed and explained in terms of a contraction of the Ag–He bonding length and a consequent confinement of the s valence electrons in silver clusters. Likewise, the Mie–Gans predictions combined with our TDDFT calculations also show that the dielectric effect produced by the He matrix is considerably less important in explaining the redshifting observed in the optical spectra of Agn@He60 clusters.
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Publication: Article
1624014936874
June 18, 2021
/research/publications/a-first-principles-study-of-the-influence-of-helium-atoms-on-the-optical-response-of-small-silver-clusters
Optical excitation spectra of Agn and Agn@He60 (n = 2, 8) clusters are investigated in the framework of the time-dependent density functional theory (TDDFT) within the linear response regime. We have performed the ab initio calculations for two different exact exchange functionals (GGAexact and LDA-exact). The computed spectra of Agn@He60 clusters with the GGA-exact functional accounting for exchange-correlation effects are found to be generally in a relatively good agreement with the experiment. A strategy is proposed to obtain the ground-state structures of the Agn@He60 clusters and in the initial rocess of the geometry optimization, the He environment is simulated with buckyballs. A redshift of the silver clusters spectra is observed in the He environment with respect to the ones of bare silver clusters. This observation is discussed and explained in terms of a contraction of the Ag–He bonding length and a consequent confinement of the s valence electrons in silver clusters. Likewise, the Mie–Gans predictions combined with our TDDFT calculations also show that the dielectric effect produced by the He matrix is considerably less important in explaining the redshifting observed in the optical spectra of Agn@He60 clusters. - M. Pereiro,D. Baldomir, and J. E. Arias - 10.1063/1.3556821
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