Geometry optimization, HOMO and LUMO energy, molecular electrostatic potential, NMR, FT-IR and FT-Raman analyzes on 4-nitrophenol

¹ Department of Physics, AMET University, Kanathur, Chennai 603112, India
² Crystal Growth Centre, Anna University, Chennai 600025, India
³ Department of Physics, Government Arts College for Women, Pudukkottai, India

^a e-mail: crystgandhi@gmail.com

Received: 30 October 2014
Accepted: 24 December 2014
Published online: 27 January 2015

Abstract

In the present work, the equilibrium geometry, HOMO-LUMO energy gap, chemical shifts, vibrational frequencies, IR and Raman intensities and thermodynamic parameters of 4-nitrophenol molecule was calculated using the methods of HF and DFT/B3YLP employing 6-311+G basis set. Theoretically calculated geometrical parameters such as bond length and bond angle were compared with the corresponding experimental X-ray diffraction values. The highest occupied (HOMO) and the lowest unoccupied molecular orbitals (LUMO) of the 4-NP molecule have been calculated. The study was extended to calculate the energy gap, ionization potential, electron affinity and chemical hardness. HOMO-LUMO electronic transition of 3.76 eV is obtained from the contribution of the bands. The reacting electrophilic and nucleophilic sites of the molecule were analyzed with the help of molecular electrostatic potential (MEP) surface analysis. The different proton and carbon environment of the grown crystal was analyzed by ¹H and ¹³C NMR analyses. All vibrational frequencies were assigned and compared with the calculated frequencies in detail.