Infrared spectrum of the compound, penty1-4-benzoyl-1-[2,4-dinitrophenyl]-5-phenyl-1H-pyrazole-3carboxylate (PBDPPC) has been measured. Conformational search through relaxed scan has been carried out to find the most stable conformational isomer. After the full geometry optimization for the most stable conformer using B3LYP and BLYP hybrid functionals of Density Functional Theory (OFT), vibrational normal modes have been calculated at the same theoretical levels. Potential Energy Distribution (PED) of each normal mode has been calculated by means of VEDA4 to obtain contributions of internal coordinates to the normal modes. Natural Bond Orbital (NBO) analysis has been performed to get insights into the possible hydrogen bonding sites for all the conformational isomers. (C) 2013 Elsevier B.V. All rights reserved.