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/core/cartesian_site_forces
Definition name: cartesian_site_forces
Property name: Cartesian site forces
Description: The force on every site of a structure (the negative gradient of the total energy with respect to the Cartesian position of each site), in electronvolt per angstrom.
Type: list
Implementation requirements:
- Support: OPTIONAL support in implementations, i.e., MAY be null.
Requirements/Conventions:
dim_sites of vectors over dim_spatial: one 3-vector per site, in the Cartesian frame of the structure the value belongs to (the frame of lattice_vectors and cartesian_site_positions).atomic_force, which is the per-atom base of this property.A null value means the quantity is not available or not recorded.
Examples:
JSON definition:
{
"$id": "https://schemas.httk.org/defs/v0.1/properties/core/cartesian_site_forces",
"$schema": "https://schemas.optimade.org/meta/v1.3/optimade/property_definition.json",
"title": "Cartesian site forces",
"x-optimade-type": "list",
"x-optimade-definition": {
"kind": "property",
"version": "0.1.0",
"format": "1.3",
"name": "cartesian_site_forces",
"label": "cartesian_site_forces_core_httk"
},
"x-optimade-unit": "angstrom^-1*eV",
"x-optimade-unit-definitions": [
{
"$id": "https://schemas.optimade.org/defs/v1.2/units/si/general/angstrom",
"title": "\u00e5ngstr\u00f6m",
"symbol": "angstrom",
"display-symbol": "\u00c5",
"description": "A unit of length equal to 10\u207b\u00b9\u2070 meter, using the current, or one of the historical, definitions of the SI units.\n\nThe \u00e5ngstr\u00f6m unit appears in the International System of Units (SI), 1st ed. (1970) defined as \"1 \u00c5 = 0.1 nm = 10\u207b\u00b9\u2070 m\".\n\nThe \u00e5ngstr\u00f6m unit was implicitly redefined via the redefinition of the metre at the 17th CGPM meeting (1983), resolution 1.\n\n- The International System of Units (SI), 1st ed. (1970) categorizes the unit as \"temporarily admitted\" for use with the SI units.\n- The International System of Units (SI), 7th ed. (1998) changes the categorization to \"Other non-SI units currently accepted for use with the International System.\"\n- The International System of Units (SI), 8th ed. (2006) changes the categorization to \"Other non-SI units\" and adds as a clarifying footnote \"The \u00e5ngstr\u00f6m is widely used by x-ray crystallographers and structural chemists because all chemical bonds lie in the range 1 to 3 \u00e5ngstr\u00f6ms. However it has no official sanction from the CIPM or the CGPM.\"\n- The \u00e5ngstr\u00f6m is omitted in the International System of Units (SI), 9th Edition (2019).\n\nThis is a generalized definition taken to reference the current, or one of the historical, SI unit definitions.\nThis definition is intended for situations when it is not possible to be more precise, e.g., in contexts where data have been collected that uses different historical SI definitions.",
"compatibility": [
"https://schemas.optimade.org/defs/v1.2/units/si/1970/temporary/angstrom",
"https://schemas.optimade.org/defs/v1.2/units/si/1983/temporary/angstrom"
],
"resources": [
{
"relation": "Definition in the International System of Units (SI), 1st Edition",
"resource-id": "https://www.bipm.org/en/publications/si-brochure"
},
{
"relation": "Redefinition of the metre at the 17th CGPM meeting (1983), resolution 1",
"resource-id": "https://www.bipm.org/en/committees/cg/cgpm/17-1983/resolution-1"
},
{
"relation": "Wikipedia article describing the unit",
"resource-id": "https://en.wikipedia.org/wiki/Angstrom"
}
],
"defining-relation": {
"base-units": [
{
"symbol": "m",
"id": "https://schemas.optimade.org/defs/v1.2/units/si/general/metre"
}
],
"base-units-expression": "m",
"scale": {
"exponent": -10
}
},
"x-optimade-definition": {
"label": "angstrom_si_general",
"kind": "unit",
"format": "1.2",
"version": "1.2.0",
"name": "angstrom"
}
},
{
"$id": "https://schemas.optimade.org/defs/v1.2/units/si/general/electronvolt",
"title": "electron volt",
"symbol": "eV",
"display-symbol": "eV",
"description": "A unit of energy that representing the kinetic energy acquired by an electron as it accelerates through a 1 volt potential difference in a vacuum using the current, or one of the historical, definitions given in the editions of the International System of Units (SI).\n\nThe electronvolt unit appears in the International System of Units (SI), 1st ed. (1970) defined as \"1 electronvolt is the energy acquired by an electron after traversing a potential difference of 1 V in a vacuum; 1 eV = 1.60219\u00d710\u207b\u00b9\u2079 J approximately.\"\nThis definition makes the unit equal to 1 volt times the value of the elementary charge.\nIn the 2019 redefinition of the SI units the elementary charge is exactly 1.602176634\u00b710\u207b\u00b9\u2079 C, making the electron volt exactly equal to 1.602176634\u00b710\u207b\u00b9\u2079 J.\nThe International System of Units (SI), 9th ed. (2019) accordingly notes the exact relationship with the SI 2019 derived unit joule as \"1 eV = 1.602176634\u00b710\u207b\u00b9\u2079 J\" but retains the definition from 1970 in a footnote.\n\nThe unit is categorized in the International System of Units (SI), 9th ed. (2019) as \"Non-SI units accepted for use with the SI units\".\n\nThis is a generalized definition taken to reference the current, or one of the historical, SI unit definitions.\nThis definition is intended for situations when it is not possible to be more precise, e.g., in contexts where data have been collected that uses different historical SI definitions.",
"compatibility": [
"https://schemas.optimade.org/defs/v1.2/units/si/1970/accepted/electronvolt",
"https://schemas.optimade.org/defs/v1.2/units/si/1983/accepted/electronvolt",
"https://schemas.optimade.org/defs/v1.2/units/si/2019/accepted/electronvolt"
],
"resources": [
{
"relation": "Definition in the International System of Units (SI), 9th Edition",
"resource-id": "https://www.bipm.org/en/publications/si-brochure"
},
{
"relation": "Wikipedia article describing the unit",
"resource-id": "https://en.wikipedia.org/wiki/Electronvolt"
}
],
"approximate-relations": [
{
"base-units": [
{
"symbol": "V",
"id": "https://schemas.optimade.org/defs/v1.2/units/si/general/volt"
},
{
"symbol": "e",
"id": "https://schemas.optimade.org/defs/v1.2/constants/codata/2018/electromagnetic/elementarycharge"
}
],
"base-units-expression": "e*V"
}
],
"x-optimade-definition": {
"label": "electronvolt_si_general",
"kind": "unit",
"format": "1.2",
"version": "1.2.0",
"name": "electronvolt"
}
}
],
"x-optimade-requirements": {
"support": "may",
"sortable": false,
"query-support": "none"
},
"x-optimade-dimensions": {
"names": [
"dim_sites",
"dim_spatial"
],
"sizes": [
null,
3
]
},
"type": [
"array",
"null"
],
"items": {
"x-optimade-type": "list",
"x-optimade-unit": "inapplicable",
"x-optimade-dimensions": {
"names": [
"dim_spatial"
],
"sizes": [
3
]
},
"type": [
"array"
],
"items": {
"x-optimade-type": "float",
"x-optimade-unit": "angstrom^-1*eV",
"type": [
"number"
]
}
},
"description": "The force on every site of a structure (the negative gradient of the total energy with respect to the Cartesian position of each site), in electronvolt per angstrom.\n\n**Requirements/Conventions**:\n\n- The value is a list over the dimension `dim_sites` of vectors over `dim_spatial`: one 3-vector per site, in the Cartesian frame of the structure the value belongs to (the frame of `lattice_vectors` and `cartesian_site_positions`).\n- The list MUST have one vector per site of that structure, in the order of its sites. The structure is the input structure of the calculation the value is a product of, as that calculation read it.\n- The force on one atom is the singular property `atomic_force`, which is the per-atom base of this property.\n\nA null value means the quantity is not available or not recorded."
}