httk property definitionsProperty definitions using the OPTIMADE property definition format, hosted by httk
This page documents an OPTIMADE Property Definition. See https://schemas.optimade.org/ for more information.
ID: https://schemas.httk.org/defs/v0.1/properties/spacegroups/harker_planes
Definition name: harker_planes
Property name: Harker planes
Description: Harker planes of the space group in fractional Patterson coordinates.
Type: list
Each entry describes one plane or special-position condition with an expression and optional exact normal, point, and constant data.
A Harker plane contains Patterson displacement vectors between symmetry-related sites.
For a contributing operation (W,w), those displacements are parameterized by (W-I)*x+w; the algebraic rendering may reverse parameter signs without changing the plane.
The current generator emits the cctbx plane descriptors algebraic, normal, and point; the optional xyz and const fields are retained but are not emitted.
Here normal is the direct-lattice direction returned by cctbx for the rotation axis, and point is a fractional point on the plane.
For lattice metric g, a displacement u lies in that plane when normal^T*g*(u-point) = 0; the fractional components of normal must not be treated as a Cartesian unit normal or a reciprocal covector.
The list covers planes constructed by cctbx's Harker-plane routine; it is not an enumeration of all Patterson peaks, Harker lines, or special points.
Examples:
[{"algebraic": "2*x,0,2*z", "normal": [0, 1, 0], "point": ["0", "0", "0"]}]JSON definition:
{
"$id": "https://schemas.httk.org/defs/v0.1/properties/spacegroups/harker_planes",
"$schema": "https://schemas.optimade.org/meta/v1.3/optimade/property_definition.json",
"title": "Harker planes",
"x-optimade-type": "list",
"x-optimade-definition": {
"kind": "property",
"version": "0.1.0",
"format": "1.3",
"name": "harker_planes",
"label": "harker_planes_spacegroups"
},
"x-optimade-unit": "inapplicable",
"type": [
"array",
"null"
],
"description": "Harker planes of the space group in fractional Patterson coordinates.\n\nEach entry describes one plane or special-position condition with an expression and optional exact normal, point, and constant data.\n\nA Harker plane contains Patterson displacement vectors between symmetry-related sites.\nFor a contributing operation `(W,w)`, those displacements are parameterized by `(W-I)*x+w`; the algebraic rendering may reverse parameter signs without changing the plane.\nThe current generator emits the cctbx plane descriptors `algebraic`, `normal`, and `point`; the optional `xyz` and `const` fields are retained but are not emitted.\nHere `normal` is the direct-lattice direction returned by cctbx for the rotation axis, and `point` is a fractional point on the plane.\nFor lattice metric g, a displacement u lies in that plane when `normal^T*g*(u-point) = 0`; the fractional components of `normal` must not be treated as a Cartesian unit normal or a reciprocal covector.\nThe list covers planes constructed by cctbx's Harker-plane routine; it is not an enumeration of all Patterson peaks, Harker lines, or special points.",
"items": {
"x-optimade-type": "dictionary",
"x-optimade-unit": "inapplicable",
"type": [
"object",
"null"
],
"description": "One Harker plane or special-position condition.",
"properties": {
"algebraic": {
"x-optimade-type": "string",
"x-optimade-unit": "inapplicable",
"type": [
"string",
"null"
],
"description": "Algebraic expression for the condition when emitted by cctbx."
},
"xyz": {
"x-optimade-type": "string",
"x-optimade-unit": "inapplicable",
"type": [
"string",
"null"
],
"description": "Optional plane expression in `x,y,z` notation; not emitted by the current generator."
},
"normal": {
"x-optimade-type": "list",
"x-optimade-unit": "inapplicable",
"x-optimade-dimensions": {
"names": [
"dim_lattice"
],
"sizes": [
3
]
},
"type": [
"array",
"null"
],
"description": "Integer direct-lattice direction normal to the plane in the physical metric, following cctbx's rotation-axis convention.",
"items": {
"x-optimade-type": "integer",
"x-optimade-unit": "inapplicable",
"type": [
"integer"
],
"description": "One integer component of the normal vector."
}
},
"point": {
"x-optimade-type": "list",
"x-optimade-unit": "inapplicable",
"x-optimade-dimensions": {
"names": [
"dim_lattice"
],
"sizes": [
3
]
},
"type": [
"array",
"null"
],
"description": "Point on the plane.",
"items": {
"$id": "https://schemas.httk.org/defs/v0.1/properties/core/fraction",
"title": "Fraction",
"x-optimade-type": "string",
"x-optimade-definition": {
"label": "fraction_core",
"kind": "property",
"version": "0.1.0",
"format": "1.3",
"name": "fraction"
},
"type": [
"string",
"null"
],
"description": "A numerical representation formed as the quotient of two numbers represented as a string.",
"examples": [
"2/3",
"5/42",
"10",
"0"
],
"x-optimade-unit": "inapplicable"
}
},
"const": {
"$id": "https://schemas.httk.org/defs/v0.1/properties/core/fraction",
"title": "Fraction",
"x-optimade-type": "string",
"x-optimade-definition": {
"label": "fraction_core",
"kind": "property",
"version": "0.1.0",
"format": "1.3",
"name": "fraction"
},
"type": [
"string",
"null"
],
"description": "A numerical representation formed as the quotient of two numbers represented as a string.",
"examples": [
"2/3",
"5/42",
"10",
"0"
],
"x-optimade-unit": "inapplicable"
}
}
},
"examples": [
[
{
"algebraic": "2*x,0,2*z",
"normal": [
0,
1,
0
],
"point": [
"0",
"0",
"0"
]
}
]
]
}