Experimental and Theoretical Vibrational Frequencies and Molecular Structure of Nicotinic Acid

The ground state molecular structure, vibrational frequencies and the corresponding assignments of the nicotinic acid (vitamin B3) have been investigated using the Hartree-Fock (HF) and density functional methods (B3LYP) with 6-311++G(d,p) basis set. The calculated vibrational frequencies and optimized geometric parameters (bond lengths and bond angles) seemed to be in good agreement with the experimental data. The comparison of the observed and calculated results showed that B3LYP is superior to the scaled HF method. Theoretical infrared intensities and Raman activities were also reported