2020/12/11 by N. Ben Amor, Amor, Nadia Ben, Eric Michoulier +3
Earth and Planetary Sciences · Physics and Astronomy · #Advanced Chemical Physics Studies #Atmospheric Ozone and Climate #Atmospheric chemistry and aerosols #Chemical Physics (physics.chem-ph) #FOS: Physical sciences
paper · pdf · doi:10.48550/arxiv.2012.06612
openalex publication_date 2020/12/11 · openalex created_date 2022/07/25 · openalex updated_date 2026/07/28
This work is dedicated to the theoretical investigation of the influence of\nwater clusters' organisation and size on the electronic spectrum of an\ninteracting benzene (Bz) molecule using both TD-DFT and CASPT2 approaches. Two\nseries of geometries, namely GeoIEI and GeoIED were extracted from\ntwo Bz-hexagonal ice configurations leading to maximum and minimum ionization\nenergies respectively. An appropriate basis set containing atomic diffuse and\npolarisation orbitals and describing the Rydberg states of Bz was determined.\nThe TD-DFT approach was carefully benchmarked against CASPT2 results for the\nsmallest systems.Despite some discrepancies, the trends were found to be\nsimilar at both levels of theory: the positions and intensities of the main\n\π \→ \π\⋆ transitions were found slightly split due to\nsymmetry breaking. For the smallest systems, our results clearly show the\ndependence of the electronic transitions on the clusters' structures. Of\nparticular interest, low energy transitions of non negligible oscillator\nstrength from a Bz \π orbital to a virtual orbital of Rydberg character,\nalso involving atomic diffuse functions and partially expanded on the water\ncluster, were found for the GeoIED series. The energies of such\ntransitions were determined to be more than 2 ,eV below the ionization\npotential of Bz. When the cluster's size increases, similar transitions were\nfound for all structures, the virtual orbitals becoming mainly developed on the\nH atoms of the water molecules at the edge of the cluster. Given their nature\nand energy, such transitions could play a role in the photochemistry of\naromatic species in interaction with water clusters or ice, such processes\nbeing of astrophysical interest.\n