site coordinate span (property)

{
    "$id": "https://schemas.optimade.org/defs/v1.3/properties/optimade/structures/site_coordinate_span",
    "$schema": "https://schemas.optimade.org/meta/v1.2/optimade/property_definition.json",
    "title": "site coordinate span",
    "x-optimade-type": "string",
    "x-optimade-definition": {
        "label": "site_coordinate_span_optimade_structures",
        "kind": "property",
        "version": "1.3.0",
        "format": "1.2",
        "name": "site_coordinate_span"
    },
    "type": [
        "string",
        "null"
    ],
    "description": "Indicates the extent of the material (crystal) described in the response.\nIn particular, properties `cartesian_site_positions` and `fractional_site_positions` MUST contain all sites *belonging* to the described extent.\n\nThe value of this property MUST be one of the following:\n\n  * `fundamental_domain`: means that sites described in the response span a fundamental domain (Vinberg, 1994; European Mathematical Society, 2020) of a periodic system.\n    When a server indicates this span in the response, it MUST provide those sites that enable reconstruction of the whole periodic system by applying symmetry operations from `space_group_symmetry_operations_xyz` property and then applying translations given by `lattice_vectors`.\n    The fundamental domain does not need to be a connected space region.\n\n  * `asymmetric_unit`: all sites are in a simply connected space region that is a fundamental domain, as per IUCr Online Dictionary of Crystallography definition (IUCr, 2017).\n\n  * `molecular_fundamental_domain`: a fundamental domain where all atoms connected by covalent or donor-acceptor coordination bonds are adjacent to each other, placed at a bond distance.\n\n  * `molecular_asymmetric_unit`: an asymmetric unit (a simply connected fundamental domain) where all atoms bound by covalent or donor-acceptor coordination bonds are adjacent to each other, placed at a bond distance.\n\n  * `unit_cell`: a full unit cell of a periodic system (crystal), i.e., any repeating unit chosen by the server defined by the property `lattice_vectors`.\n    For this span, the server MUST provide a set of sites in the response that can be used to reconstruct the whole periodic system (crystal) by simply applying translations from the `lattice_vectors` property to those sites.\n\n  * `molecular_unit_cell`: same as `unit_cell`, but in addition places atoms that are bound by covalent or coordination bonds at a bond distance from each other.\n\n  * `molecular_entities`: sets of atoms that are bound by covalent or coordination bonds, as per IUPAC definition of a 'molecular entity'.\n    This set of sites MAY be larger than a fundamental domain.\n\n  * `other`: any other collection of sites that does not fit the enumerated values above.\n\n  * `null`: if omitted or `null`, the default value of `site_coordinate_span` is `unit_cell`.\n    This is the assumed behavior of all main implementations before the `site_coordinate_span` definition was introduced.\n\n**Note**: In all cases it is RECOMMENDED that only the minimal set of the sites that is needed to reconstruct the whole material is provided.\nFor example, for the 'unit_cell' span the server SHOULD NOT return sites that can be obtained from other returned sites through the translations given in `lattice_vectors`; only a non-redundant set of sites SHOULD be provided.\n\n**Bibliographic References**:\n\nE.B. Vinberg (originator). (1994) Encyclopedia of Mathematics. ISBN `1402006098 <https://isbnsearch.org/isbn/1402006098>`__, URL: https://encyclopediaofmath.org/index.php?title=Fundamental_domain&oldid=13590 [accessed 2025-04-30T08:55+03:00].\n\nEuropean Mathematical Society (2020). Fundamental domain. Encyclopedia of Mathematics. URL: http://encyclopediaofmath.org/index.php?title=Fundamental_domain&oldid=47023 [accessed 2025-04-30T08:53+03:00].\n\nIUCr (2017). Asymmetric unit. Online Dictionary of Crystallography, URL: https://dictionary.iucr.org/Asymmetric_unit [accessed 2025-04-30T09:01+03:00].",
    "examples": [
        "asymmetric_unit",
        "unit_cell"
    ],
    "x-optimade-unit": "inapplicable",
    "enum": [
        "fundamental_domain",
        "asymmetric_unit",
        "molecular_fundamental_domain",
        "molecular_asymmetric_unit",
        "unit_cell",
        "molecular_unit_cell",
        "molecular_entities",
        "other"
    ]
}