New Trends in Determination of Crystal Structure

Abstract

Direct methods1 have become dominant in the determination of well-ordered crystal structures. They are based on an estimate of seminvariant values from distributions of seminvariants.* From any seminvariant one can thus form an equation $$ {{f}_{i}}({{\varphi }_{1}}, \ldots ,{{\varphi }_{n}}) = {{\Phi }_{i}}\pm {{d}_{i}}, $$ (1) where Фi is the expected value of seminvariant and di. is an unknown error related statistically to the distribution width. (When fi is a periodic function, the right side has to be taken modulo.)