list of Hill chemical formula (property)

This page documents an OPTIMADE Property Definition. See https://schemas.optimade.org/ for more information.

ID: https://schemas.optimade.org/defs/v1.3/properties/optimade/trajectories/chemical_formula_hill
Definition name: chemical_formula_hill

Property name: list of Hill chemical formula
Description: A list of chemical_formula_hill items. A chemical_formula_hill item is the chemical formula for a structure in Hill form with element symbols followed by integer chemical proportion numbers for elements which do not have proportion 1.
Type: list

For each chemical_formula_hill item the following applies:

Requirements/Conventions:

Query examples:

Examples:

Formats: [JSON] [MD]

JSON definition:

{
    "$id": "https://schemas.optimade.org/defs/v1.3/properties/optimade/trajectories/chemical_formula_hill",
    "$schema": "https://schemas.optimade.org/meta/v1.3/optimade/property_definition.json",
    "title": "list of Hill chemical formula",
    "x-optimade-type": "list",
    "x-optimade-definition": {
        "label": "chemical_formula_hill_optimade_trajectories",
        "kind": "property",
        "version": "1.3.0",
        "format": "1.3",
        "name": "chemical_formula_hill"
    },
    "x-optimade-dimensions": {
        "names": [
            "dim_frames"
        ],
        "sizes": [
            null
        ],
        "compactable": [
            "constant"
        ]
    },
    "type": [
        "array",
        "null"
    ],
    "description": "A list of chemical_formula_hill items.\nA chemical_formula_hill item is the chemical formula for a structure in [Hill form](https://dx.doi.org/10.1021/ja02046a005) with element symbols followed by integer chemical proportion numbers for elements which do not have proportion 1.\n\nFor each chemical_formula_hill item the following applies:\n\n**Requirements/Conventions**:\n\n- The proportion number MUST be omitted if it is 1.\n- The overall scale factor of the chemical proportions is chosen such that the resulting values are integers that indicate the most chemically relevant unit of which the system is composed.\n  For example, if the structure is a repeating unit cell with four hydrogens and four oxygens that represents two hydroperoxide molecules, `chemical_formula_hill` is `\"H2O2\"` (i.e., not `\"HO\"`, nor `\"H4O4\"`).\n- If the chemical insight needed to ascribe a Hill formula to the system is not present, the property MUST be handled as unset.\n- Element symbols MUST have proper capitalization (e.g., `\"Si\"`, not `\"SI\"` for \"silicon\").\n- Elements MUST be placed in [Hill order](https://dx.doi.org/10.1021/ja02046a005>), followed by their integer chemical proportion number.\n  Hill order means: if carbon is present, it is placed first, and if also present, hydrogen is placed second.\n  After that, all other elements are ordered alphabetically.\n  If carbon is not present, all elements are ordered alphabetically.\n- If the system has sites with partial occupation and the total occupations of each element do not all sum up to integers, then the Hill formula SHOULD be handled as unset.\n- No spaces or separators are allowed.\n\n**Query examples**:\n\n- A filter that matches an exactly given formula is `chemical_formula_hill=\"H2O2\"`.",
    "examples": [
        [
            "H2O2"
        ]
    ],
    "x-optimade-unit": "inapplicable",
    "items": {
        "$id": "https://schemas.optimade.org/defs/v1.2/properties/optimade/structures/chemical_formula_hill",
        "title": "Hill chemical formula",
        "x-optimade-type": "string",
        "x-optimade-definition": {
            "label": "chemical_formula_hill_optimade_structures",
            "kind": "property",
            "version": "1.2.0",
            "format": "1.2",
            "name": "chemical_formula_hill"
        },
        "type": [
            "string",
            "null"
        ],
        "description": "The chemical formula for a structure in [Hill form](https://dx.doi.org/10.1021/ja02046a005) with element symbols followed by integer chemical proportion numbers. The proportion number MUST be omitted if it is 1.\n\n**Requirements/Conventions**:\n\n- The overall scale factor of the chemical proportions is chosen such that the resulting values are integers that indicate the most chemically relevant unit of which the system is composed.\n  For example, if the structure is a repeating unit cell with four hydrogens and four oxygens that represents two hydroperoxide molecules, `chemical_formula_hill` is `\"H2O2\"` (i.e., not `\"HO\"`, nor `\"H4O4\"`).\n- If the chemical insight needed to ascribe a Hill formula to the system is not present, the property MUST be handled as unset.\n- Element symbols MUST have proper capitalization (e.g., `\"Si\"`, not `\"SI\"` for \"silicon\").\n- Elements MUST be placed in [Hill order](https://dx.doi.org/10.1021/ja02046a005>), followed by their integer chemical proportion number.\n  Hill order means: if carbon is present, it is placed first, and if also present, hydrogen is placed second.\n  After that, all other elements are ordered alphabetically.\n  If carbon is not present, all elements are ordered alphabetically.\n- If the system has sites with partial occupation and the total occupations of each element do not all sum up to integers, then the Hill formula SHOULD be handled as unset.\n- No spaces or separators are allowed.\n\n**Query examples**:\n\n- A filter that matches an exactly given formula is `chemical_formula_hill=\"H2O2\"`.",
        "examples": [
            "H2O2"
        ],
        "x-optimade-unit": "inapplicable"
    }
}