Method in Mechanical Vibration Theory and Studies of Properties of Straight-chain Alkanes

A molecule of straight-chain alkanes was regarded as a multi-dimension system in mechanic vibration. A atom, or atomic group was regarded as the dispersion mass-point in it. The chemical bond in molecules was like the spring combining the dispersion mass-point. The intrinsic vibrational frequency was calculated by transmit matrix method. The change relation of the intrinsic vibration with the structure unit was discussed. It is found that there are good relationships between the fundamental frequencies and the structural properties of straight-chain alkanes, and between the sum-frequencies and the additivity properties of straight-chain alkanes as well. Combining the fundamental frequency and the sum-frequency, the relation model of the condensation properties with the fundamental frequency and sum-frequency can reflects the change law between the properties and intrinsic frequencies awfully nice. The quantitative relation model was established between the fundamental or sum frequency and properties of straight-chain alkanes. Some properties of straight-chain alkanes were predicted by the model. The results showed that there was very close relation between the frequency and the properties, and the coefficient r>0.999.