In this paper we present a detailed computational study of the electronic structure and optical properties of triply-bonded hydrocarbons with linear, and graphyne substructures, with the aim of identifying their potential in opto-electronic device applications. For the purpose, we employed a correlated electron methodology based upon the Pariser-Parr-Pople model Hamiltonian, coupled with the configuration interaction (CI) approach, and studied structures containing up to 42 carbon atoms.Our calculations, based upon large-scale CI expansions, reveal that the linear structures have intense optical absorption at the HOMO-LUMO gap, while the graphyne ones have those at higher energies. Thus, the opto-electronic properties depend on the topology of the graphyne substructures, suggesting that they can be tuned by means of structural modifications. Our results are in very good agreement with the available experimental data.
We have performed the first principles electron-correlated calculations employing large basis sets to optimize the geometries, and to compute linear optical absorption spectra of various lowlying conformers of silicon hydrides: Si 2 H 2n , n = 1, 2, 3. The geometry optimization for various isomers was carried out at the coupled-cluster singles-doubles-triples [CCSD(T)] level of theory, while their excited states and absorption spectra were computed using large-scale multi-reference singles-doubles configuration-interaction (MRSDCI) approach, which includes electron-correlation effects at a sophisticated level. Our calculated spectra are the first ones for Si 2 H 2 and Si 2 H 4 conformers, while for Si 2 H 6 we obtain excellent agreement with the experimental measurements, suggesting that our computational approach is reliable. Our calculated absorption spectra exhibit a strong structure-property relationship, suggesting the possibility of identifying various conformers based on their optical absorption fingerprints. We also believe that our results will be useful for optical identification of hydrogenation induced defects in silicon thin films. arXiv:1807.11197v1 [physics.atm-clus] 30 Jul 2018
Using periodic density functional theory-based calculations, in the present study, we address the chemical bonding between aluminium clusters (Aln, n = 4–8 and 13) and monovacant defective graphene.
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