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/electronic/relative_effective_mass
Definition name: relative_effective_mass
Property name: Relative effective mass
Description: The effective-mass tensor of one band at the wavevector center, relative to the free-electron mass: m/m_e = m_e^-1 hbar^2 (d^2E/dk_i dk_j)^-1, the inverse of the band-energy curvature matrix at center. center is in angstrom^-1 (2 pi included); tensor is dimensionless.
The tensor is signed: negative values correspond to hole-like (downward) curvature, and mixed-sign eigenvalues occur at saddle points. Where the curvature matrix is singular the effective mass is undefined and the value is null.
A null value means the quantity is not available or not recorded.
Type: dictionary
Implementation requirements:
- Support:* OPTIONAL support in implementations, i.e., MAY be null.
Examples:
JSON definition:
{
"$id": "https://schemas.httk.org/defs/v0.1/properties/electronic/relative_effective_mass",
"$schema": "https://schemas.optimade.org/meta/v1.3/optimade/property_definition.json",
"title": "Relative effective mass",
"x-optimade-type": "dictionary",
"x-optimade-definition": {
"kind": "property",
"version": "0.1.0",
"format": "1.3",
"name": "relative_effective_mass",
"label": "relative_effective_mass_electronic_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"
}
}
],
"x-optimade-requirements": {
"support": "may",
"sortable": false,
"query-support": "none"
},
"type": [
"object",
"null"
],
"description": "The effective-mass tensor of one band at the wavevector `center`, relative to the free-electron mass: m*/m_e = m_e^-1 hbar^2 (d^2E/dk_i dk_j)^-1, the inverse of the band-energy curvature matrix at `center`. `center` is in angstrom^-1 (2 pi included); `tensor` is dimensionless.\nThe tensor is signed: negative values correspond to hole-like (downward) curvature, and mixed-sign eigenvalues occur at saddle points. Where the curvature matrix is singular the effective mass is undefined and the value is null.\nA null value means the quantity is not available or not recorded.",
"required": [
"center",
"tensor"
],
"properties": {
"center": {
"x-optimade-type": "list",
"x-optimade-unit": "inapplicable",
"x-optimade-dimensions": {
"names": [
"dim_spatial"
],
"sizes": [
3
]
},
"type": [
"array"
],
"description": "Cartesian wavevector at which the tensor is evaluated, in reciprocal angstrom with the factor 2 pi included (k = 2 pi / wavelength), in the Cartesian frame of the referenced cell.",
"items": {
"x-optimade-type": "float",
"x-optimade-unit": "angstrom^-1",
"type": [
"number"
],
"description": "One Cartesian component of the wavevector."
}
},
"tensor": {
"x-optimade-type": "list",
"x-optimade-unit": "inapplicable",
"x-optimade-dimensions": {
"names": [
"dim_spatial"
],
"sizes": [
3
]
},
"type": [
"array"
],
"description": "The 3x3 relative effective-mass tensor, rows and columns over `dim_spatial` in the Cartesian frame of the referenced cell.",
"items": {
"x-optimade-type": "list",
"x-optimade-unit": "inapplicable",
"x-optimade-dimensions": {
"names": [
"dim_spatial"
],
"sizes": [
3
]
},
"type": [
"array"
],
"description": "One row of the tensor.",
"items": {
"x-optimade-type": "float",
"x-optimade-unit": "dimensionless",
"type": [
"number"
],
"description": "One tensor component."
}
}
}
}
}