Vibrational spectra (FT-IR and FT-Raman), molecular structure, natural bond orbital, and TD-DFT analysis of l-Asparagine Monohydrate by Density Functional Theory approach

• A detailed interpretation of Infrared and Raman spectra of LAM were reported.
• The first order hyperpolarizability of LAM were calculated.
• NBO, HOMO and LUMO analysis were also performed by DFT approach.

In this work we report the vibrational spectral analysis of l-Asparagine Monohydrate (LAM) molecule by using FT-IR and FT-Raman spectroscopic techniques. The equilibrium geometry, harmonic vibrational wavenumbers, various bonding features have been computed using density functional B3LYP method with 6-311G(d,p) as basis set. Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. The results show that charge in electron density (ED) in σ* and π* antibonding orbitals and second order delocalization energies E(2) confirms the occurrence of Intramolecular Charge Transfer (ICT) within the molecule. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) complements with the experimental findings. The simulated spectra satisfactorily coincide with the experimental spectra.

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