On lithium doping in two stable nano-flakes of the B₂₄: The double-ring versus the quasiplanar configuration

The stable local minima due to the addition of the Li atom to the double-ring and the quasiplanar configurations of the B₂₄ molecule have been searched on the doublet potential energy surface to reveal the structural and electronic features of the Li@B₂₄ system. We report two and seven stable local minima without imaginary vibrational frequency for the Li@B₂₄(double-ring) and the Li@B₂₄(quasiplanar) systems, respectively. The criteria of the adsorption energy, the vertical ionization (VI) energy, the deformation energy, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy gap, the atomic charges, the spin density distribution, the electron transfer (ET), atoms in molecules (AIM) analysis and the nonlinear optical (NLO) properties have been investigated for all the reported molecules of the Li@B₂₄ system in the present paper. Our results present that both thermodynamic and chemical stability of the Li atom doping to the quasiplanar configuration of the B₂₄ molecule are more than those of the double-ring configuration. Additionally, both the double-ring and the quasiplanar configurations can produce the Li@B₂₄ system with values of high first hyperpolarizability (β_total) due to the Li atom doping. In all the reported molecules of the Li@B₂₄ system, electron density of the Li atom decreases due to the existence of the double-ring and the quasiplanar configurations confirming the role of the electron donor for the Li atom. In contrast, both decreasing and increasing electron density have been observed in the B atoms of the Li@B₂₄ system. However, the role of electron acceptor (increasing electron density) for the B atoms is more dominant than the role of electron donor (decreasing electron density). This result highlights chemical flexibility of the B atoms.