Applying Group Theory To Analyse Molecular Vibrational Modes

Both IR spectrum and Raman spectrum are vibrational spectrum..The mostimportant application of IR spectrum is configuration identify of organic compound ininfrared area. We can make certain configuration of compound by comparing withnormal spectral chart; For unknown sample, wo can guess configuration byconfiguration information of substitute place and hydrogen bond combination. Ramanspectrum technology is developed in recent years, and effect is more and moreimportant. Raman spectrum has its own superiority by comparing with IRspectrum. .Raman spectrum is an important analytic method of modern laser spectraltechnique, for the sake of its special advantages(e.g. independent of molecular energylevels),it is applied widely in solution, gases, isotopes, elemental crystal and so on.. Inthe recent years surface-enhanced raman spectrum, resonance raman spectrumtechnique etc. are developed in succession, and the laser raman spectrum is appliedmore and more in macromolecule structural analytic field, now raman spectralapplication involves chemical, physical and biological domain. In this paper we analyze mainly propylene 15 normol vibration modes and itsspectral properties by group theory, and compare with result of gaussian soft withcomputer, and find it correctly. We obtain conclusion: The 15 normal vibrationalmodes of propylene are all raman active. If we want to conclude accurate result, wemust calculate dynamics equation and educe vibrational frequency. In this paper wemake use of GF matrix, construct G matrix F matrix, and put them into equation, thenwe can obtain vibrational frequency of molecule.