KARLE-HAUPTMAN MATRICES AND EIGENVALUES - A PRACTICAL APPROACH

The possible usefulness of eigenvectors and eigenvalues of Karle-Haupt man matrices is examined. The eigenvalue spectra of structures with ca lculated and measured \U\'s are discussed and the result of several at tempts at phase refinement are reported. The use of the sum of the squ are of the negative eigenvalues (SSNE) as a goodness-of-fit criterion is examined. The possible use of a priori information is investigated using the approximation of orthogonal electron densities corresponding to eigenvectors with eigenvalues greater than zero.