∑_4关系式在确定晶体结构中的应用

THE APPLICATION OF ∑_4 RELATIONSHIP FOR THE DETERMINATION OF CRYSTAL STRUCTURE

本文在高级∑关系式最新研究成果的基础上,提出了一套可行的利用∑_4关系式计算h_1反射相角为0的概率P+(h_1)的方法,并用ALGOL-60语言编制了∑_4计算程序。用这个程序计算了EuP_5O_(14)(空间群P2_1/C)衍射数据中的27个结构半不变量的相角为0的概率。得到的相角同结构经最小二乘修正后的最后相角φ_c符合得很好,从而首次实现了∑_4关系式在确定晶体结构中的应用。

This paper, based on the latest research results for the ∑ relationships, has proposed the feasible calculation method using ∑_4 relationship for the probability P_+(h_1) of the reflection h_1 with phase angle being egual to 0. The calculation program of ∑_4 has been compiled in ALGOL-60 Ienguange. Utilizing the program we have calculated the probabilities of 27 structure semi-invariants, which are from reflection data for the EuP_5O_(14) (Spase group P2_1/C), with phase angles being equal to 0. The agreement between calculated phase angles and φ_c obtained by the least-squares is good. Therefore, we have realized the first application of ∑_4 relationship for the determination of crystal structure.