As a language model AI, I cannot perform quantum mechanical calculations directly. However, I can provide you with some general information about the vibrational frequencies and infrared spectra of acetic acid.Acetic acid CH3COOH is a relatively simple molecule with 8 atoms, which means it has 3N-6 = 18 normal modes of vibration 3N-5 = 19 for a linear molecule . These vibrational modes can be classified into different types, such as stretching, bending, and torsional vibrations.The vibrational frequencies and infrared spectra of acetic acid can be obtained using quantum mechanical methods like the Hartree-Fock method or Density Functional Theory DFT with appropriate basis sets. These calculations can be performed using computational chemistry software packages like Gaussian, ORCA, or NWChem.The vibrational frequencies obtained from these calculations will be in the form of wavenumbers cm . The infrared spectrum will show the intensity of absorption at each frequency, which can be used to identify the functional groups and molecular structure of the compound.Some of the key vibrational frequencies for acetic acid are:1. O-H stretching: around 3000-3500 cm2. C-H stretching methyl and carboxylic groups : around 2800-3000 cm3. C=O stretching carbonyl group : around 1700 cm4. C-O stretching carboxylic group : around 1200-1300 cm5. C-C stretching: around 1000-1100 cmPlease note that these values are approximate and may vary depending on the level of theory and basis set used in the calculations. To obtain accurate vibrational frequencies and infrared spectra for acetic acid, you would need to perform quantum mechanical calculations using appropriate computational chemistry software.