Theoretical thermodynamic study of Pyrazole in the gas phase at the different temperatures

The thermodynamic functions such as enthalpy (H), Gibbs free energy (G) and entropy (S) ofPyrazole was theoretically studied at 5 different temperatures 25, 30, 35, 40 and 45°C by usingGussian o3, software. First, the structural optimization of isolated Pyrazole was done in the gas phaseby appling the Density Functional Theory (B3LYP) level with 3-21G, 6-31G and 6-31+G(d) basissets. Moreover, vibrational frequencies were calculated in gas phase on the optimized geometries atthe same level of theory to obtain enthalpy, Gibbs free energy and entropy at 5 differenttemperatures.Finally the temperature effects on the thermodynamic functions were discussed.