Impact of even number of alkaline earth metal doping on the NLO response of C₂₀ nanocluster; a DFT outcome

Geometrics, electronic, optical and nonlinear properties of even number (2, 4, 6) alkaline earth metal atoms (AEM) doped C₂₀ nanocluster are analyzed through density functional theory (DFT) calculations. The interaction of even number of AEM with C₂₀ surface is highly exothermic. Among all doped M_n@C₂₀ (M = Be, Mg and Ca, n = 2, 4 and 6) nanoclusters, Be₆@C₂₀ shows highest binding energy of −241.18 kcal/mol. In all AEM-doped nanoclusters, the HOMO-LUMO (G_H-L) gap is effectively reduced which reflects the change in conducting properties. The lowest G_H-L (0.82 eV) is observed for Ca₆@C₂₀ nanocluster. The involvement of metal atoms with nanocluster is further confirmed through density of states (DOS) spectral analysis. First hyperpolarizability (β_o) is calculated to analyze the NLO response of all considered doped nanoclusters. It is observed that the doping of even number of first three AEM significantly increased the first hyperpolarizability (β_o). Ca₂@C₂₀ shows the highest hyperpolarizability value (5.86 × 10⁴ au) compared to all other nanoclusters.