Effect of order on the structure and vibrational properties of glasses. ab initio molecular orbital study; Glass ni okeru chitsujo kozo towa. Bunshi kido keisan ni yoru glass no kozo to shindo jotai no kaiseki

摘要: The structure and vibrational spectra of silica glasses were analyzed by using molecular orbital calculation that uses clusters. As a result, the two sharp peaks appearing in the Raman spectrum was elucidated to have been originated from the well-regulated ring structure existing in the glass network. Based on this result, a consideration was given on the `order structure in glasses`. The order structure in glasses is a remainder of having gone through crystallization and having reached the glass after over-cooled condition. However, the order structure is not a three dimensional translational and symmetrical structure in crystals, but would rather be a structure whose energy is stable locally as 3-4 member ring structure in silica glass, and which does not exist in corresponding crystals. In addition, the author indicated that the order structure like this could be related also with low energy excitation of 100 cm {sup -1} or lower, which is universally observed in Raman and non-elastic scattering spectra of glasses. (NEDO)