What can be computed by I.S.A.A.C.S. ?

I.S.A.A.C.S. can compute the following important structural characteristics of a 3D structure model:

• Radial distribution functions g(r) (RDFs) [7] including ^o:
  • Total RDFs for neutrons and X-rays.
  • Partial RDFs.
  • Bathia-Thornton RDFs [8]
  ^o Radial distribution functions can be computed by i) direct real space calculation and/or ii) Fourier transforming of the structure factor calculated using the Debye formalism [9]
• Structure factors S(q) [9] including ^oo:
  • Total structure factors S(q) for neutrons and X-rays.
  • Total Q(q) [9,10] for neutrons and X-rays.
  • Partial S(q):
    • Faber-Ziman [11] partial S(q)
    • Ashcroft-Langreth [12,13,14] partial S(q)
    • Bathia-Thornton [15] partial S(q)
  ^oo Structure factors can be computed by i) Fourier transforming of the radial distribution functions and/or ii) using the Debye formalism [9]
• Interatomic bond properties
  • Coordination numbers
  • Atomic near neighbor distribution
  • Fraction of links between tetrahedra
  • Fraction of tetrahedral units
  • Bond lengths distribution for the first coordination sphere
• Distribution of Bond angles
• Distribution of Dihedral angles
• Ring statistics
  According several definitions:
  • All closed paths (no rules)
  • King's rings [17,16]
  • Guttman's rings [18]
  • Primitive rings [20,19] (or Irreducible [21])
  • Strong rings [20,19]
  Also included are options for:
  • Possibility to look only for ABAB rings
  • Possibility to exclude rings with homopolar bonds (A-A or B-B) from the analysis
  Ring statistics is presented according to the R.I.N.G.S. method [22].
• Spherical harmonics invariant, Q_l, as local atomic ordering symmetry identifiers [23]
  • Average Q_l for each chemical species
  • Average Q_l for a user specified structural unit
• Bond valence sums [24,26,25]
  • Average bond valence for each chemical species
  • Average bond valence for a user specified structural unit
• Mean Square Displacement of atoms (MSD)
  • Atomic species MSD
  • Directional MSD (x, y, z, xy, xz, yz)
  • Drift of the center of mass