Intensities of X-ray scattering from a one-dimensionally disordered crystal having the multilayer averaged structure. Reduction of the number of parameters denoting the degree of disorder

In the actual interpretation of diffuse scattering of X-rays from a one-dimensionally disordered crystal by the method of Takaki & Sakurai [Acta Cryst. (1976), A32, 657-663], one of the problems is how to reduce the number of independent parameters denoting the degree of disorder. For this purpose it is assumed that J_m is real for any value of m, where J_m is the mean value of the product F^*_nF_n + m of the structure factors of two layers separated by m interlayer spaces. Several conditions for J_m to be real are presented.