Affiliations: [a] Laboratory of Computational Sciences, Department of Computer Science and Technology, Faculty of Sciences and Technology, University of Peloponnese, GR-22 100 Tripolis, Greece | [b] Division of Theoretical Chemistry, Department of General, Inorganic, and Theoretical Chemistry, University of Innsbruck, A-6020, Innrain 52a, Austria. E-mail: xenides@uop.gr | [c] Department of Physics, Faculty of Natural Sciences, University of Patras, GR-26 500 Patras, Campus at Rion, Greece. E-mail: garoufal@physics.upatras.gr | [x] Department of Chemistry, University of Patras, Greece | [y] Department of Physics, University of Patras, Greece
Abstract: The dipole polarizabilities of the pure tetramers (C4, Si4) and mixed carbon silicon hetero-clusters (CxSi4−x, 0⩽x⩽4) have been calculated within the framework of time independent and Time-Dependent (TD) Density Functional Theory (DFT) methods. The convergence of the two approaches is remarkably good revealing the absence of any systematic error. The Si- substitution leads to clusters with enhanced properties. The effect is more pronounced in the case of second hyperpolarizability (x 103 e4a04Eh−3): 8.51(C4) → 18.04(SiC3) → 32.45(Si2C2) → 60.45(Si3C) → 100.79(Si4). To further extend our study, we have performed a spectral decomposition of dipole polarizabilities by employing the TD excitation energies and their corresponding oscillator strengths. Such a decomposition allows for a pictorial insight into some of the factors controlling the evolution of the property for these clusters.
