Acta Crystallographica Section AActa Crystallographica Section A: Foundations of Crystallography publishes papers reporting fundamental advances in all areas of crystallography in the broadest sense. The central themes are, on the one hand, experimental and theoretical studies of the properties and arrangements of atoms, ions and molecules in condensed matter, ideal or real, and of their symmetry and, on the other, the theoretical and experimental aspects of the various methods to determine these arrangements.Convergence study of a Schrdinger-equation algorithm and structure-factor determination from the wavefunction- May 16, 2008 The algorithm Bethanis, Tzamalis, Hountas & Tsoucaris (2002). Acta Cryst. A58, 265269 which reformulates the quantum-mechanical problem of solving a Schrdinger (S) equation in a crystallographic context has been upgraded and tested for many aspects of convergence. The upgraded algorithm in reciprocal space aims at determining a wavefunction H such that (a) H fulfils the S equation within certain precision and (b) H minimizes by least squares the differences between the calculated structure..http://scripts.iucr.org/cgi-bin/paper?au5063 Elastic properties of two-dimensional quasicrystals- May 12, 2008 Quasicrystals (QC) with two-dimensional quasiperiodic and one-dimensional periodic structure are considered. Their symmetry can be described by embedding the three-dimensional physical space VE in a five-dimensional superspace V, which is the direct sum of VE and a two-dimensional internal space VI. A displacement v in V can be written as v = u + w, where u VE and w VI. If the QC has a point group P in VE that is crystallographic, it is assumed that w and a vector u VE lying in the plane in...http://scripts.iucr.org/cgi-bin/paper?pz5054 |