Computational Studies on Molecular Structure and Vibrational Spectra of an Organic Molecule 2-Acetylamino-Benzoic Acid Using Density Functional Theory

摘要

In this paper, we have calculated the optimized molecular geometry, atomic Mulliken charges, harmonic vibrational frequencies, thermodynamic properties, HOMO-LUMO and related molecular properties of 2-acetylamino-benzoic acid by Density functional theory (DFT) using 6-31G and 6-311G basis sets. The calculated structural parameters (bond lengths and bond angles) are in good agreement with the experimental XRD data. The vibrational unsealed wavenumbers are calculated and are scaled by a proper scaling factor of 0.962 in case of 6-31G and 0.963 in case of 6-311G. The assignments of wave numbers were made on the basis of potential energy distribution (PED) using Vibrational Energy Distribution Analysis (VEDA) program. The HOMO-LUMO study was extended to calculate various molecular parameters like ionization potential, electron affinity, global hardness, electron chemical potential, electronegativity and global electrophilicity of the given molecule. The thermodynamic properties like SCF energy, zero point vibrational energy, heat capacity, enthalpy, entropy, dipole moment and rotational constants are calculated. The total electron density, molecular electrostatic potential and electrostatic potential maps are constructed using DFT/6-311G theory.