Computational Study on Piperazine‐1,4‐Diium Acetate Using Dft Investigations: Structural Aspects, Topological and Nonlinear Optical Properties.

The work aims to investigate the nonlinear optical (NLO) activity of piperazine‐1,4‐diium acetate (PAA) molecule utilizing computational techniques. The computational calculations are performed using density functional theory (DFT) to explore the vibrational modes, electronic and NLO properties of PAA by comparing them with piperazine and acetic acid molecules. The natural bond orbital analysis is performed to identify hydrogen bonding and charge transfer interaction. A vibrational analysis is carried out and the assignment of fundamental modes is done using the vibrational energy distribution analysis (VEDA) program. Molecular electrostatic potential, frontier molecular orbital, electron localization function, localized orbital locator and Fukui analysis are carried out to identify chemical reactivity and charge transfer interaction. The UV–visible analysis is performed to obtain the electronic absorption spectrum. The hole–electron analysis is performed for the first five excitations to identify the type of excitation. The atoms in molecules, reduced density gradient and independent gradient model are performed to identify the hydrogen bonding, steric and van der Waals interactions. Hirshfeld analysis is performed to explore the intermolecular interactions within the PAA molecule. The NLO calculation is performed to evaluate the NLO parameters. The obtained results show that the PAA molecule is suitable for NLO applications. [ABSTRACT FROM AUTHOR]