期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1982
卷号：79
期号：6
页码：2125-2127
DOI：10.1073/pnas.79.6.2125
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Formulas for the cosines of the higher order phase invariants that arise in crystal structure analysis are derived as expected values from determinantal joint probability distributions. The values of the cosines of the invariants are expressed in terms of averages over simple functions of known structure factor magnitudes. The formulas are termed "general" to distinguish them from formulas that have more restricted averages and are termed "special." As with the special formulas, the best opportunity for obtaining useful information from these formulas is provided by embedded seminvariants formed from the invariants by use of relationships among the phases that arise from the space group symmetries.
关键词：embedded seminvariant ; determinantal joint probability distribution ; phase determination
