Ontology for Materials Databases Materials Databases Ontology 0.1 An isDescribedByMaterialsModel relationship states that a material is described by a materials model is described by materials model A composite materials model specify a material by a set of parameters that describe an amorphous structure. Amorphous structure materials model A composite materials model specify a material by a set of parameters that describe a composite. Composite materials model Formal definiion: A material is something that is described by a materials model. Physical description: A material is a system of atoms in a state described by a statistical distribution over 'microstates' (microscopic structure realizations). A material is distinguished from other materials by the ensemble of microstates that, due to the statistical distribution, are effectively the relevant ones in observations of the system. Two systems with distinctively different ensembles of relevant microstates are two different materials. For a system of atoms in an environment that changes (e.g. the temperature, pressure, etc.) the ensemble of relevant microstates may change. This can happen discontinuously, which represents a phase transition, or continuously over a path in the phase diagram. The ensemble of relevant microstates may contain only a single microstate. This is, depending on the periodicity, the representation of a perfect bulk single crystal, slab, wire or molecule. While the ensemble of relevant microstates defines the specific material, a material can be specified without explicitly specifying this ensemble of microstates via a materials model. Such models include the description of the material as a composite, a metallic alloy, an amorphous structure, a quasicrystal, or as the result of a synthesis process. Material Materials model A metallic alloy materials model specify a material by a set of parameters that describe a metallic alloy. Metallic alloy materials model A composite materials model specify a material by a set of parameters that describe a quasicrystal. This is done as by defining cuts in a periodic crystal in higher dimensions. Quasicrystal materials model A single structure materials model is a materials model that specify the ensemble of relevant microstates of a material as a single structure. A structure refer to the geometrical configuration of specific atomic species. It may be partially or fully periodic or non-periodic. That is, depending on the periodicity it represents a bulk single crystal, slab, wire or molecule. A structure may encompass a restricted ensemble of geometric realizations to the degree that can be described by disordered occupation on specific sites, or as disordered correlated occupations as can be described as assemblies. A structure may encompass a level of uncertainty in geometric realization with implicit atoms and site attachments. Single structure materials model A structures ensemble materials model is a materials model that explicitly specify a set of structures as forming the ensemble of relevant microstates of the material. Structures ensemble materials model A synthesis description materials model specify a material by a set of synthesis steps that, when followed, results in the synthesis of the material. Synthesis description materials model