1：Theoretical method:

Geometry optimization was performed using the data available in PubChem database without any constraints. The optimized ground state structure of the molecule was obtained by DFT method and visualized in Gauss View program. The DFT based on Becke’s three-parameter (local, non-local, HF) hybrid exchange functional with Lee–Yang–Parr correlation functional (B3LYP) was utilized. The basis set 6-311++G(d,p) augmented by ‘d’ polarization functions on heavy atoms and ‘p’ polarization functions on hydrogen atoms as well as diffuse functions for both hydrogen and heavy atoms was used.

2：NBO analysis:

The second-order micro-disturbance theory analysis was employed to study the electron donor orbital, acceptor orbital, and the interacting stabilization energy.

3：Nonlinear optical (NLO) properties:

The first hyperpolarizability (β0) of the molecular system, and the related properties; mean polarizability (α0) and anisotropy of polarizability (?α) were calculated using B3LYP/6-311++G(d,p) basis set.

4：Thermodynamic properties:

The total energy, zero-point energy, heat capacity (C0), enthalpy (H0), dipole moment, and the rotational constants of the molecular system were obtained directly from the output of Gaussian calculation employing B3LYP/6-311G(d.p) basis set.