J/A+A/668/A35ivo://CDS.VizieR/J/A+A/668/A35doi:10.26093/cds/vizier.36680035CDSSindel J.P.Gobrecht D.Helling C.Decin L.2024-11-28T20:01:27Z2022-12-02T10:04:20ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.fratomic-physicsThe formation of inorganic cloud particles takes place in several atmospheric environments, including those of warm, hot, rocky, and gaseous exoplanets, brown dwarfs, and asymptotic giant branch stars. The cloud particle formation needs to be triggered by the in situ formation of condensation seeds since it cannot be reasonably assumed that such condensation seeds preexist in these chemically complex gas-phase environments. We aim to develop a method for calculating the thermochemical properties of clusters as key inputs for modelling the formation of condensation nuclei in gases of changing chemical composition. TiO_2_ is used as benchmark species for cluster sizes N=1-15. We created a total of 90000 candidate (TiO_2_)N geometries for cluster sizes N=3-15. We employed a hierarchical optimisation approach, consisting of a force-field description, density-functional based tight-binding, and all-electron density-functional theory (DFT) to obtain accurate zero-point energies and thermochemical properties for the clusters. In 129 combinations of functionals and basis sets, we find that B3LYP/cc-pVTZ, including Grimme's empirical dispersion, performs most accurately with respect to experimentally derived thermochemical properties of the TiO_2_ molecule. We present a hitherto unreported global minimum candidate for size N=13. The DFT-derived thermochemical cluster data are used to evaluate the nucleation rates for a given temperature-pressure profile of a model hot-Jupiter atmosphere. We find that with the updated and refined cluster data, nucleation becomes unfeasible at slightly lower temperatures, raising the lower boundary for seed formation in the atmosphere. The approach presented in this paper allows finding stable isomers for small (TiO_2_)N clusters. The choice of the functional and basis set for the all-electron DFT calculations has a measurable impact on the resulting surface tension and nucleation rate, and the updated thermochemical data are recommended for future considerations.2022A&A...668A..35Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/668/A35CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/668/A35https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/668/A35http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/668/A35https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/668/A35https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/668/A35http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/668/A35GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapdefaultJ/A+A/668/A35/listList of entriesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRankRankmeta.idintClMolecular cluster identification within the rankmeta.idintCoordinatesDisplay the Coordinates for this molecular cluster and rankmeta.ref.urlcharThermochemicalDisplay the Thermochemical data for this molecular cluster and rankmeta.ref.urlcharNoteExplanation of the (Rank, Cl) codemeta.notecharJ/A+A/668/A35/coordsCoordinates (for the 246 entries)RankRankmeta.idintyy coordinate of the atom (Angstroem)0.1nmpos.cartesian.ydoublezz coordinate of the atom (Angstroem)0.1nmpos.cartesian.zdoublerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintClMolecular cluster identification within the rankmeta.idintAtomAtomic symbol of the atomphys.atmol.elementcharxx coordinate of the atom (Angstroem)0.1nmpos.cartesian.xdoubleJ/A+A/668/A35/thermoThermochemical data (for the 246 entries)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRankRankmeta.idintClMolecular cluster identification within the rankmeta.idintTTemperature TKphys.temperaturefloatSEntropy SJ.mol**-1.K**-1phys.atmoldoubleH-HoEnthalpy difference to reference temperature (298.15)kJ/molphys.atmoldoubleDfHEnthalpy of formationkJ/molphys.atmoldoubleDfGGibbs free energy of formationkJ/molphys.atmoldouble