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/transport/mean_squared_displacement
Definition name: mean_squared_displacement
Property name: Mean squared displacement
Description: Mean squared displacement tensor as a function of lag time.
Type: dictionary
Implementation requirements:
- Support: OPTIONAL support in implementations, i.e., MAY be null.
All lists of the dictionary share the dimension _httk_dim_lags; lag_times gives the lag time of each entry.
Requirements/Conventions:
lag_times (ps) are the lag times.msd (angstrom^2) is the mean over atoms and time origins of the displacement tensor Delta r_i Delta r_j, where Delta r is the displacement over the lag. Each tensor member has the shared lag dimension first, followed by two dim_spatial axes (Cartesian x, y, z) giving the tensor components; the tensor is not symmetrized.origin_counts (optional, dimensionless integers) gives the number of time origins averaged for each lag.A null value means the quantity is not available or not recorded.
Examples:
JSON definition:
{
"$id": "https://schemas.httk.org/defs/v0.1/properties/transport/mean_squared_displacement",
"$schema": "https://schemas.optimade.org/meta/v1.3/optimade/property_definition.json",
"title": "Mean squared displacement",
"x-optimade-type": "dictionary",
"x-optimade-definition": {
"kind": "property",
"version": "0.1.0",
"format": "1.3",
"name": "mean_squared_displacement",
"label": "mean_squared_displacement_transport_httk"
},
"x-optimade-unit": "inapplicable",
"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/prefixes/si/pico",
"title": "pico",
"symbol": "p",
"display-symbol": "p",
"description": "The pico SI prefix defined as a dimensionless multiple of 10\u207b\u00b9\u00b2, adopted into SI at its creation at the 11th CGPM Meeting in 1960, resolution 12.",
"resources": [
{
"relation": "Definition in the 11th CGPM Meeting in 1960, resolution 12",
"resource-id": "https://www.bipm.org/en/committees/cg/cgpm/11-1960/resolution-12"
},
{
"relation": "Wikipedia article describing the SI prefixes",
"resource-id": "https://en.wikipedia.org/wiki/Metric_prefix"
}
],
"defining-relation": {
"base-units": [],
"base-units-expression": "",
"scale": {
"exponent": -12
}
},
"x-optimade-definition": {
"label": "pico_prefix_si",
"kind": "prefix",
"format": "1.2",
"version": "1.2.0",
"name": "pico"
}
},
{
"$id": "https://schemas.optimade.org/defs/v1.2/units/si/general/second",
"title": "second",
"symbol": "s",
"display-symbol": "s",
"description": "A unit of time using the current, or one of the historical, definitions of the SI units.\n\nThe current definition in its most recent phrasing at the 26th CGPM Meeting in 2018, resolution 1 is: \"The second, symbol s, is the SI unit of time. It is defined by taking the fixed numerical value of the caesium frequency, \\(\\Delta \\nu_\\textrm{Cs}\\), the unperturbed ground-state hyperfine transition frequency of the caesium 133 atom, to be 9192631770 when expressed in the unit Hz, which is equal to s\u207b\u00b9.\"\n\nThis is a rephrasing of a definition at the 13th CGPM Meeting (1967), resolution 1: \"The second is the duration of 9192631770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom.\"\n\nThe earlier definition at the 11th CGPM Meeting in 1960, resolution 9 was: \"The second is the fraction 1/31556925.9747 of the tropical year for 1900 January 0 at 12 hours ephemeris time.\"\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/1960/base/second",
"https://schemas.optimade.org/defs/v1.2/units/si/1967/base/second"
],
"resources": [
{
"relation": "Definition in the 13th CGPM Meeting (1967), resolution 1",
"resource-id": "https://www.bipm.org/en/committees/cg/cgpm/13-1967/resolution-1"
},
{
"relation": "Rephrased definition in the 26th CGPM Meeting (2018), resolution 1",
"resource-id": "https://www.bipm.org/en/committees/cg/cgpm/26-2018/resolution-1"
},
{
"relation": "Definition at the 11th CGPM meeting (1960), resolution 6.",
"resource-id": "https://www.bipm.org/en/committees/cg/cgpm/11-1960/resolution-6"
},
{
"relation": "Wikipedia article describing the unit",
"resource-id": "https://en.wikipedia.org/wiki/Second"
}
],
"x-optimade-definition": {
"label": "second_si_general",
"kind": "unit",
"format": "1.2",
"version": "1.2.0",
"name": "second"
}
}
],
"x-optimade-requirements": {
"support": "may",
"sortable": false,
"query-support": "none"
},
"type": [
"object",
"null"
],
"required": [
"lag_times",
"msd"
],
"description": "Mean squared displacement tensor as a function of lag time.\n\nAll lists of the dictionary share the dimension `_httk_dim_lags`; `lag_times` gives the lag time of each entry. \n\n**Requirements/Conventions**:\n\n- `lag_times` (ps) are the lag times.\n- `msd` (angstrom^2) is the mean over atoms and time origins of the displacement tensor Delta r_i Delta r_j, where Delta r is the displacement over the lag. Each tensor member has the shared lag dimension first, followed by two `dim_spatial` axes (Cartesian x, y, z) giving the tensor components; the tensor is not symmetrized.\n- `origin_counts` (optional, dimensionless integers) gives the number of time origins averaged for each lag.\n\nA null value means the quantity is not available or not recorded.",
"properties": {
"lag_times": {
"x-optimade-type": "list",
"x-optimade-unit": "inapplicable",
"x-optimade-dimensions": {
"names": [
"_httk_dim_lags"
],
"sizes": [
null
]
},
"type": [
"array"
],
"items": {
"x-optimade-type": "float",
"x-optimade-unit": "ps",
"type": [
"number"
]
}
},
"msd": {
"x-optimade-type": "list",
"x-optimade-unit": "inapplicable",
"x-optimade-dimensions": {
"names": [
"_httk_dim_lags"
],
"sizes": [
null
]
},
"type": [
"array"
],
"items": {
"x-optimade-type": "list",
"x-optimade-unit": "inapplicable",
"x-optimade-dimensions": {
"names": [
"dim_spatial"
],
"sizes": [
3
]
},
"type": [
"array"
],
"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^2",
"type": [
"number"
]
}
}
}
},
"origin_counts": {
"x-optimade-type": "list",
"x-optimade-unit": "inapplicable",
"x-optimade-dimensions": {
"names": [
"_httk_dim_lags"
],
"sizes": [
null
]
},
"type": [
"array"
],
"items": {
"x-optimade-type": "integer",
"x-optimade-unit": "dimensionless",
"type": [
"integer"
]
}
}
}
}