{ "$id": "https://schemas.httk.org/defs/v0.1/properties/energetics/convex_hull_phase_diagram", "$schema": "https://schemas.optimade.org/meta/v1.3/optimade/property_definition.json", "title": "Convex-hull phase diagram", "x-optimade-type": "dictionary", "x-optimade-definition": { "kind": "property", "version": "0.1.0", "format": "1.3", "name": "convex_hull_phase_diagram", "label": "convex_hull_phase_diagram_energetics_httk" }, "x-optimade-unit": "inapplicable", "x-optimade-unit-definitions": [ { "$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" }, "type": [ "object", "null" ], "required": [ "elements", "compositions", "energies_per_atom", "energies_above_hull_per_atom", "stable", "tolerance" ], "description": "A convex-hull phase diagram over a set of phases with known energies.\n\nLists `phase_ids`, `energies_per_atom`, `energies_above_hull_per_atom` and `stable` share the dimension `_httk_dim_phases`; `compositions` has dimensions `_httk_dim_phases` then `_httk_dim_elements`; `elements` has the dimension `_httk_dim_elements`. They MUST have consistent lengths.\n\n**Requirements/Conventions**:\n\n- `elements` are the element labels, sorted by code point. Phases whose energy is unknown are excluded from the hull and from all lists here, but their elements may still widen `elements`.\n- `phase_ids` (optional) are caller labels of the phases, possibly not unique.\n- `compositions` (dimensionless) are atomic fractions of each phase over `elements`.\n- `energies_per_atom` (eV) are the per-atom energies on the caller's consistent linear energy scale (total or formation energy); only hull distances are independent of that scale.\n- `energies_above_hull_per_atom` (eV) holds, for each phase, the nonnegative `energy_above_hull_per_atom` of that phase against the other listed phases.\n- `stable` states, for each phase, whether its energy excess over the hull is at most `tolerance`; a stable phase may therefore have a small positive hull distance, and polymorphs tied within `tolerance` are all stable.\n- `tolerance` (eV) is the maximum energy excess treated as stable.\n\nA null value means the quantity is not available or not recorded.", "properties": { "elements": { "x-optimade-type": "list", "x-optimade-unit": "inapplicable", "x-optimade-dimensions": { "names": [ "_httk_dim_elements" ], "sizes": [ null ] }, "type": [ "array" ], "items": { "x-optimade-type": "string", "x-optimade-unit": "inapplicable", "type": [ "string" ] } }, "phase_ids": { "x-optimade-type": "list", "x-optimade-unit": "inapplicable", "x-optimade-dimensions": { "names": [ "_httk_dim_phases" ], "sizes": [ null ] }, "type": [ "array" ], "items": { "x-optimade-type": "string", "x-optimade-unit": "inapplicable", "type": [ "string" ] } }, "compositions": { "x-optimade-type": "list", "x-optimade-unit": "inapplicable", "x-optimade-dimensions": { "names": [ "_httk_dim_phases" ], "sizes": [ null ] }, "type": [ "array" ], "items": { "x-optimade-type": "list", "x-optimade-unit": "inapplicable", "x-optimade-dimensions": { "names": [ "_httk_dim_elements" ], "sizes": [ null ] }, "type": [ "array" ], "items": { "x-optimade-type": "float", "x-optimade-unit": "dimensionless", "type": [ "number" ] } } }, "energies_per_atom": { "x-optimade-type": "list", "x-optimade-unit": "inapplicable", "x-optimade-dimensions": { "names": [ "_httk_dim_phases" ], "sizes": [ null ] }, "type": [ "array" ], "items": { "x-optimade-type": "float", "x-optimade-unit": "eV", "type": [ "number" ] } }, "energies_above_hull_per_atom": { "x-optimade-type": "list", "x-optimade-unit": "inapplicable", "x-optimade-dimensions": { "names": [ "_httk_dim_phases" ], "sizes": [ null ] }, "type": [ "array" ], "items": { "x-optimade-type": "float", "x-optimade-unit": "eV", "type": [ "number" ] } }, "stable": { "x-optimade-type": "list", "x-optimade-unit": "inapplicable", "x-optimade-dimensions": { "names": [ "_httk_dim_phases" ], "sizes": [ null ] }, "type": [ "array" ], "items": { "x-optimade-type": "boolean", "x-optimade-unit": "inapplicable", "type": [ "boolean" ] } }, "tolerance": { "x-optimade-type": "float", "x-optimade-unit": "eV", "type": [ "number" ] } } }