Electronic and Optical Properties of Copper Nanostructures for Advanced Applications

Abstract

This study presents a comprehensive quantum computational investigation into the electronic structure, topological characteristics, and optical properties of two distinct series of copper hydride nanoclusters [Cu3L3(H)i(BH4)j]+ and[Cu3L2(H)i(BH4)j]+ where, i=0 to 2 and j=0 and 1. The electronic stability and reactivity are systematically evaluated through chemical hardness and chemical potential analyses, revealing that [Cu3L3(H)(BH4)]+ exhibits the highest electronic stability, whereas [Cu3L2(H)(BH4)]+ displays the greatest susceptibility to electronic perturbations. To gain deeper insights into the nature of the M-L interactions, EDA-NOCV is employed, demonstrating a pronounced covalent character in the bonding interaction between the copper center and the ligand fragments. The linear and nonlinear optical parameters have been rigorously computed under both static and dynamic regimes. Notably, [Cu3L2(H)]+, [Cu3L2(H)(BH4)]+and [Cu3L3(H)]+ exhibit remarkably high first hyperpolarizability (βtot0), reaching up to 1500 a.u., whereas Cu3L2(H)2 presents the lowest βtot0 value (166 a.u.). These significant variations in NLO activity are attributed to the intrinsic topological framework of the nanoclusters, coupled with kinetic and potential energy at the AIM critical points BCPs and RCPs, which critically modulate charge delocalization and electron density redistribution. Additionally, the pronounced polarizability anisotropy observed in [Cu3L2(H)]+ and [Cu3L2(H)(BH4)]+ is identified as a key factor in increasing their NLO efficiency. Furthermore, second-order hyperpolarizability analysis indicates that Cu3L3 exhibits the highest value (173.48 × 10⁴ a.u.), whereas Cu3L2(H)2 presents the lowest (5.688 × 10⁴ a.u.). Frequency-dependent analyses at laser wavelengths of 1340 nm and 1064 nm reveal a pronounced enhancement of dynamic hyperpolarizability over its static counterpart. Moreover, TD-DFT calculations validate the exceptional Near-Infrared (NIR) transparency of these nanoclusters. Specifically, nanoclusters [Cu3L3(H)(BH4)]+, [Cu3L3(H)2]+, [Cu3L2(H)2]+ and [Cu3L2(H)]+, exhibit outstanding transparency across both the NIR and visible spectral regions, underscoring their potential for advanced applications in nonlinear optics and optoelectronic devices.