The oxygen atoms of cubic ZrO
2 form a primitive cubic (pc) lattice. Two positions of the pc lattice are occupied by metal atoms in the perovskite-related structures (PER group) of superconducting ...oxides. Many ZrO
2-related structures with ordered oxygen defects □ like Zr
3Sc
4□
2O
12 or Cu
2O□
3 and most superconducting oxides can be characterized by the ordering of the defects and oxygen atoms. The structures are analyzed by the self-coordination numbers
T
i
of the oxygen atoms with other oxygen atoms in the
i=1–3 coordination shell and the
T
1,
T
2 values plotted in structure maps. The
T
i
values can be correlated with attractive or repulsive interactions and the mobility of oxygen atoms. The different structures can be classified in about 20 structure families like the Ruddlesden–Popper phases. The characterization by sequences of structural units or sequences of coordination numbers allows the search for new compounds with high oxygen mobility.
The sequences of bases A, T, C and G of about 100 enolase,
secA and cytochrome DNA were analyzed for attractive or repulsive interactions by the numbers
T
1,T
2,T
3;
r
of nearest, next-nearest and ...third neighbor bases of the same kind and the concentration
r=other bases/analyzed base. The area of possible
T
1,
T
2 values is limited by the linear borders
T
2=2T
1−2,
T
2=0
or
T
1=0 for clustering, attractive or repulsive interactions and the border
T
2=−2
T
1+2(2−
r) for a variation from repulsive to attractive interactions at
r⩽2. Clustering is preferred by most bases in sequences of enolases and
secA’
s. Major deviations with repulsive interactions of some bases are observed for archaea bacteria in
secA and for highly developed animals and the human species in enolase sequences. The borders of the structure map for enthalpy stabilized structures with maximum interactions are approached in few cases. Most letters of the natural languages and some music notes are at the borders of the structure map.
Two- and Three-Dimensional Surfaces Hauck, J.; Mika, K.
Zeitschrift für physikalische Chemie (Neue Folge),
01/2002, Volume:
216, Issue:
11
Journal Article
Peer reviewed
The periodic zero-potential surfaces were calculated for 17 two- and 84 three-dimensional structures A
with
=
and identical neighborhood of all atoms. The structures can be characterized by Dirichlet ...domains as structural units with
= 0 − 6 openings to neighboring domains. Some structures correspond to circle or sphere packings with
contacts to neighboring circles or spheres. 58 other structures with
> 1 contain different structural units for A and B domains.
This chapter provides a discussion of how informatics tools can address one of the fundamental historical developments in crystal chemistry, that of structure maps. Such maps serve as a means to ...explore how specific parameters associated with crystal and electronic structure can serve as a way to rationalize groupings, or classifications, relating structure and chemistry. Historically, structure maps have evolved through a variety of heuristic approaches that define a priori how parameters may be important, and then classifications are discovered as one populates these maps with data. The resulting clustering of data serves as a heuristic tool to rationalize new discoveries and new structure–bonding relationships.
Magnetic ordering Hauck, J; Mika, K
Journal of magnetism and magnetic materials,
04/2000, Volume:
212, Issue:
3
Journal Article
Peer reviewed
The ordering of magnetic moments in about 60 compounds containing M=Cr, Mn, Fe, Co, Ni, Pd, rare earths or U is analyzed by the self-coordination numbers of nearest, second and third neighbor ...positions
T
1,
T
2,
T
3 and the ratio
r=
y/
x of the equivalent positions
x and remaining positions
y. The plot of
T
1,
T
2 values for primitive cubic or hexagonal, face-centered or body-centered cubic lattices shows similar structures as in ordered alloys with small
T
2 values for attractive interactions and large
T
2 values at repulsive interactions. The intermediate interactions with
T
1,
T
2 values at the border of the structure map can be described by structure families with a combination of structural units.
Structure maps are presented as an efficient means of indicating structure-reactivity relationships in metabolic pathway databases. The relative occurrence of N-demethylation and N-oxidation of ...N-methyl tertiary amines was examined using the structure map methodology. A new family of reaction site representations, the n-level representations, was developed to describe the N-methyl reaction sites of the compounds in the data set. It was possible to differentiate N-demethylation and N-oxidation reaction sites using a structure map constructed from a 3-level representation of the reaction sites.
