The intrinsic stability of metallocarbohedrenes, combined with their structural flexibility for functionalization, positions these nanomaterials as promising candidates for nonlinear optical (NLO) applications. In the present study, a series of donor–acceptor (D-A) assemblies with high NLO potential were theoretically designed and investigated using first-principles density functional theory (DFT) calculations. Hence, titanium carbide nanoclusters, regarding to their low ionization potential, ion emission capability, high thermal conductivity, exceptional hardness, and corrosion resistance, are systematically investigated. To evaluate the dynamic NLO response of the titanium carbide nanoclusters, frequency-dependent properties including electro-optical Pockels effect (EOPE), second harmonic generation (SHG), hyper-Rayleigh scattering (HRS), dc-Kerr coefficients, electric field-induced second harmonic generation (ESHG), and nonlinear refractive index (n2) are assessed. Our results revealed that in most cases, SHG exhibited a stronger NLO response than EOPE and HRS at the incident wavelength of the Nd:YAG laser. Furthermore, we propose an effective strategy for developing D-A assemblies with enhanced NLO performance by linking superalkalis (Li3O, Na3O, K3O, LiBe, LiMg, LiCa, Li2F, and Li3F) and superhalogens (BeF3, MgF3, CaF3, and LiF2) to a diverse set of titanium carbide nanoclusters (TixCy; x = 3–8, 11–14, 17, 19 and y = 2, 7–8, 10, 12–14). The resulting complexes exhibit large binding energies, reflecting strong interactions between TixCy nanoclusters and the considered superatoms. Our findings indicate that functionalization with superalkalis and superhalogens effectively narrows the HOMO–LUMO energy gap and significantly enhances the first hyperpolarizability (β0) of pristine TixCy nanoclusters, primarily due to electron transfer from the attached superatoms. Among the examined systems, K3O-functionalized complexes exhibit the highest β0 particularly K3O-Ti12C13 and K3O-Ti13C13, which are attributed to efficient charge transfer and reduced energy gaps. The present study provides theoretical insight that inspires experimental efforts toward the synthesis of titanium carbide and highlights their promising potential as active materials for second harmonic generation (SHG) applications.

Nonlinear optical responses of superatom-metallocarbohedrene assemblies

期刊论文
发表日期：

2026年7月6日

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Hadise Soleymani,
Akbar Omidvar

摘要

The intrinsic stability of metallocarbohedrenes, combined with their structural flexibility for functionalization, positions these nanomaterials as promising candidates for nonlinear optical (NLO) applications. In the present study, a series of donor–acceptor (D-A) assemblies with high NLO potential were theoretically designed and investigated using first-principles density functional theory (DFT) calculations. Hence, titanium carbide nanoclusters, regarding to their low ionization potential, ion emission capability, high thermal conductivity, exceptional hardness, and corrosion resistance, are systematically investigated. To evaluate the dynamic NLO response of the titanium carbide nanoclusters, frequency-dependent properties including electro-optical Pockels effect (EOPE), second harmonic generation (SHG), hyper-Rayleigh scattering (HRS), dc-Kerr coefficients, electric field-induced second harmonic generation (ESHG), and nonlinear refractive index (n₂) are assessed. Our results revealed that in most cases, SHG exhibited a stronger NLO response than EOPE and HRS at the incident wavelength of the Nd:YAG laser. Furthermore, we propose an effective strategy for developing D-A assemblies with enhanced NLO performance by linking superalkalis (Li₃O, Na₃O, K₃O, LiBe, LiMg, LiCa, Li₂F, and Li₃F) and superhalogens (BeF₃, MgF₃, CaF₃, and LiF₂) to a diverse set of titanium carbide nanoclusters (Ti_xC_y; x = 3–8, 11–14, 17, 19 and y = 2, 7–8, 10, 12–14). The resulting complexes exhibit large binding energies, reflecting strong interactions between Ti_xC_y nanoclusters and the considered superatoms. Our findings indicate that functionalization with superalkalis and superhalogens effectively narrows the HOMO–LUMO energy gap and significantly enhances the first hyperpolarizability (β₀) of pristine Ti_xC_y nanoclusters, primarily due to electron transfer from the attached superatoms. Among the examined systems, K₃O-functionalized complexes exhibit the highest β₀ particularly K₃O-Ti₁₂C₁₃ and K₃O-Ti₁₃C₁₃, which are attributed to efficient charge transfer and reduced energy gaps. The present study provides theoretical insight that inspires experimental efforts toward the synthesis of titanium carbide and highlights their promising potential as active materials for second harmonic generation (SHG) applications.