keywords
chiral
This selects
all structures from chiral space groups (those with only proper operations, viz. rotation, screw or translation).
chathrate
This term is
used to refer to 4-coordinated nets based on simple tilings by polyhedra with
faces with up to 6 sides. mtn and mep
are the nets of types I and II clathrate hydrates.
good
"good"
structures have all shortest distances corresponding to equal lengths and the
next shortest distance > 1.4 times as large, and/or have the order of the
point symmetry at the vertices > 7.
heterocoord
This refers to
mixed coordination (e.g. 4- and 8- coordinated). for 3,4-, 3,6- and
4,6-coordinated use the keywords "heterocoord 34", "heterocoord 36" and
"heterocoord 46".
infinite
polyhedron
An infinite
polyhedron is a tiling of a 3-periodic surface. See O'Keeffe, M.; Hyde, B. G. Crystal
Structures I: Patterns and Symmetry. Washington. Mineral. Soc. Am. (1996). We have not systematically
searched for these.
interpenetrating
net
These are
structure with two, or more, interpenetrating nets of the same kind. Note that
the symmetry is generally different from that of a single net. These all have
symbols ending in -c
or –cn. The means there are n (>2) interpenetrating nets.
isohedral
tiling
These are
structures for which the normal tiling consists of one kind of tile with all
tiles related by a symmetry operation (tile transitive).
polar
This selects
nets with polar symmetry (i.e. those of classes 1, 2, m, 3, 3m, 4, 4m, 6, 6m).
regular net
There are 5
regular nets in which the vertices have a regular polygon or polyhedron as
vertex figure. For their natural tilings the transitivity is 1111.
Delgado-Friedrichs, O. F.; O'Keeffe, M.; Yaghi, O. M. Acta Crystallogr. 2003, A59, 22-27. [transitivity pqrs means p kinds of vertex, q kinds of edge, r kinds of tile face, s kinds of tile]
rod net
In rod nets
vertices lie on straight, non-intersecting lines.
self dual
net
A self-dual
net is a net that has a tin that tiling is self-dual. In some cases the
self-dual tiling is not the natural one and is given in parentheses in
"tiling".
semiregular
net
Semiregular
nets have one kind of vertex and one kind of edge (vertex and edge transitive,
or transitivity 11rs)
Delgado-Friedrichs, O. F.; O'Keeffe, M.; Yaghi, O. M. Acta Crystallogr. 2003, A59, 515-525.
simple
tiling
In a simple
tiling 2 tiles meet at a face, 3 at an edge and 4 at a vertex. the tiles are
simple polyhedra (1 faces meet at each edge and 3 at each vertex). There are
nine vertex-transitive simple tilings [choose keyword "simple tiling"
and nets with one kind of vertex]. Their duals are the nine ways of tiling
space with congruent polyhedra. See Delgado-Friedrichs, O.; Huson, D. H. Discr.
Comp. Geom. 1999, 21, 299-315. Delgado-Friedrichs, O.;
O'Keeffe, M. Acta Cryst. 2005,
A61, 358-362.
uniform net
In a uniform
net the shortest rings contained in each angle are the same size. See
especially A. F. Wells, Three dimensional nets and polyhedra. Wiley, New York 1977.
uniform
tiling
In a uniform
tiling, all the vertices are the same (uninodal or vertex transitive) and the
tiles are all uniform polyhedra (vertex transitive with regular polygonal
faces). Grünbaum, B. Geombinatorics 1994,
4, 49-56. Deza, M.;
Shtogrin, M. Eur. J. Combinatorics 2000,
21, 807-814.
The
correspondence with Grünbaum's numbers are: 1: fcu 2: hcp 3: tcd 4: tca 5: flu-e 6: crs 7: reo 8: cab 9: reo-e 10: ubt 11: hex 12: tsi 13: svk 14: sve 15: svh 16: tfs 17: svj 18: kag 19: ttw 20: pcu-i 21: hal 22: pcu 23: fst 24: fee 25: lta 26: hex 27: rho 28: sod
zeolite net
These nets
appear in the Atlas of Zeolite Structure Types
http://www.iza-structure.org/databases/. Note that we always use a maximum
symmetry configuration. Generally we only include zeolite nets with one or two
kinds of vertex.