Superatom Compounds under Oriented External Electric Fields: Simultaneously Enhanced Bond Energies and Nonlinear Optical Responses

Abstract

It has recently been demonstrated that oriented external electric fields (OEEFs) can serve as future smart reagents and effectors in chemistry. Consequently, the effect of OEEFs on the geometric structures, electronic properties, bonding properties, and NLO responses of three typical superatom compounds, i.e., (NLi4)(BF4) and (BLi6)X (X = BeF3 and BF4) has been systemically investigated by ab initio computations in this work. The computational results reveal that the (NLi4)(BF4) possesses almost the same performance as the traditional alkali metal halide under the same OEEFs. It is found that the vertical ionization potential, bond energy, and first hyperpolarizability of (NLi4)(BF4) can be gradually enhanced by increasing the imposed OEEF from zero to the critical external electric field (Fc) along the charge transfer direction (NLi4 → BF4). In particular, the first hyperpolarizability of (NLi4)(BF4) is greatly enlarged from 2.84 × 103 to 1.36 × 107 au (4790-fold) by increasing OEEF from 0 to 121 × 10–4 au. Moreover, a similar effect is also observed for (BLi6)X. Consequently, this work reveals an effective approach to simultaneously enhance the bond energies and NLO responses of superatom compounds through imposing OEEFs along the charge transfer direction.