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The First Table of Atomic Site Coordinates of the Ih QC (4)
https://doi.org/10.5281/zenodo.23426598
The First Table of Atomic Site Coordinates of the Ih Quasicrystal | Zenodo
The atomic site coordinate data in the first Table are all computer-generated.
230空间群表描述的是理想的晶体,理想的占位,晶体中没有任何缺陷,如位错或层错,等等。只有理想的才是普遍的,才能覆盖一切的,具有形形色色缺陷的晶体。
准晶体的第1表,也是如此,描述的是理想的准晶体,理想的原子占位,理想的准晶体中没有任何缺陷,包括局域对称性破损的缺陷。只有理想的点阵模型,才能描述具有形形色色缺陷的准晶体,和晶体的理想点阵模型是一样的。
因此,是实际的准晶体向理想的点阵模型靠拢,而非理想的点阵模型向具有缺陷的实验室的准晶体靠拢。
实验室的晶体也是如此,你声称你具有Oh点群对称性,你不能自己检验自己吧。让谁来检验?只有230空间群,因为230空间群知道谁最有资格成为Oh点群晶体。
实验室的准晶体(Ih) 也是如此,你声称你具有Ih点群对称性,你不能自己用你自己的衍射数据检验自己吧。你必须要和具有Ih点群对称性的理想点阵来比对,因为你有大量的形形色色的缺陷,是你的缺陷导致你和理想的Ih点群准晶体有点差距,因为实验误差是难免的。
实验室的准晶体(Ih)声称自己满足Ih点群对称性,言外之意,就是宣布准晶体自己要向理想的点阵靠拢。
啥是理想的准晶体(Ih)的点阵,就是要绝对地满足Ih点群的对称性,就这一个条件。毫无疑问,满足了这个条件,原子点位自然而然地就会充满整个空间。空间群的理想晶体也是如此,实验室的Oh点群立方晶体,只要声称自己具有Oh点群对称性,就要想方设法消除实验误差,让自己向理想的Oh晶体靠拢。
这就是理想晶体(准晶体)的点阵模型的意义。
Within the framework of the n-Shell Lattice Model, once the value of n is specified, a computer can immediately output the Atomic Sites corresponding to the n-th Shell, generate the absolute Cartesian coordinates for the n-th Shell of the quasicrystal Cell, and ultimately—by applying the Ih point group—derive the absolute Cartesian coordinates of all Atomic Sites within that quasicrystal (Ih).
For a quasicrystal of a given size, it is possible to generate the coordinates of the atomic sites corresponding to that size. This is the promise of the first table.
In fact, the 230 space groups are also described in this way—they are capable of filling the entire space.
Undoubtedly, being able to fill an entire space is one thing; whether that space ought to be filled is quite another.
When addressing practical problems, whether or not space should be filled depends on physics—not on the space groups, nor is it determined by the first table.
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