The dynamical theory of the diamond lattice. I

7. Summary

(1) The theoretical calculations of the characteristic frequency of diamond and the experimental results of the vibration spectra of diamond are reviewed in brief; (Section 1).

(2) The vibratory equations of motion of the diamond lattice under the three forces’ system and the suitable type of intra-valence forces are formulated. A typical factor of the secular equation is then obtained and it is found that it corresponds to the vibration of the two component cubic facecentred lattices composing the diamond lattice relative to one another, each being considered as rigid. The said vibration is triply degenerate. It appears that this vibration is Raman-active but optically inactive since all the atoms are homonuclear. Hence an explanation for the origin of the principal Raman line with the shift 1332 cm.⁻¹ and the absence of the infra-red band corresponding to 1332 cm.⁻¹ follows.