Enhancement of nonlinear optical response of 26Adamanzane by doping with alkali metals exohedrally and alkaline earth metals endohedrally: a DFT study

Abstract

The quest for nonlinear optical (NLO) crystals, which are essential for future optical understanding, detailed evaluations, and present laser gadgets, is a prominent concern in the materials investigation. In this systematic analytical evaluation, the optical, electrical, and nonlinear optical (NLO) parameters of 2⁶Adamanzne which was doped endohedrally with alkaline earth and exohedrally with alkali metals, resulted with nine electron-rich complexes Mº(2⁶ADZ)M (where (Mº = Be, Mg, Ca) and (M = Li, K, Na)), were designed. Geometrical, thermodynamic, and electronic computations executed through density functional theory (DFT) and 6-31G (d,p) basis set. All metals doped 2⁶ADZ are within the range of effective NLO materials such as a lowered band gap in the range of 6.22–3.86 eV which was very higher in case of pure surface. At the same level of theory, transition density matrix (TDM), non-covalent interaction analysis (NCI), and electron density distribution map (EDDM) were carried out. The NBO analysis anticipated the charge transfer between donor and acceptor moieties. Computational investigations like binding energy (E_b), interaction energy, and vertical ionization potential confirm the high stability of the proposed complexes. The UV-visible assessment reveals that all complexes are transparent in the ultraviolet range and have maximum absorptivity up to 1009 nm (visible and NIR range). Doping techniques in all complexes profoundly impacted the oscillator strength and dipole moment, leading to an escalating value of hyperpolarizability β_tot up to 421.042 × 10⁻³⁰ esu. The optical efficiency of proposed complexes is approximated by using the value of isotropic linear polarizability (α_iso) which is boosted from 2.538 × 10⁻³⁰ to 8.665 × 10⁻²³ esu. The strong optical response of Mº(2⁶ADZ)M suggests its potential as a promising candidate for nonlinear optics, paving the way for synthesizing additional materials with practical applications in optoelectronics.