## structure-hexagonal-crystal-npt

Property Definition (short name) A common way to refer to the Property Definition. Note there may be multiple Property Definitions with the same short name, to fully distinguish between Property Definitions the full Tag URI must be used (the Property Definition ID). structure-hexagonal-crystal-npt tag:staff@noreply.openkim.org,2014-04-15:property/structure-hexagonal-crystal-npt Equilibrium hexagonal crystal structure at a given temperature and stress state Conventional lattice parameters of a hexagonal crystal at a given temperature and stress state. karls karls 2014-04-15 Property Definition Physics Validator Property Documentation Wiki
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#### Property Definition Keys

Required Optional

#### basis-atom-coordinates

type float false [":" 3] true Fractional coordinates of the basis atoms in the conventional unit cell. If the unit cell vectors are denoted by , , and , and the fractional coordinates of atom 'i' are [afrac_i, bfrac_i, cfrac_i], the value of 'basis-atom-coordinates' will be of the form [[afrac_1 bfrac_1 cfrac_1] [afrac_2 bfrac_2 cfrac_2] ... ]. All components of each basis atom should be between zero and one, inclusive of zero.

#### c

type float true [] true The average length of unit cell vector . The associated direction must correspond to the third component of the entries of 'basis-atom-coordinates'. The triad (,,) must form a right-handed system.

#### cauchy-stress

type float true [6] true The [xx,yy,zz,yz,xz,xy] (i.e. [11,22,33,23,13,12]) components of the Cauchy stress acting on the periodic cell. The orthonormal basis (,,) used to express the stress should be such that e_1 is in the direction of , e_3 is in the direction of , and e_2 is in the direction of ( x ). The expected form should be [d d e 0 0 r].

#### species

type string false [":"] true The element symbols of the basis atoms. The order in which the species are specified must correspond to the order of the atoms listed in 'basis-atom-coordinates'.

#### temperature

type float true [] true Temperature of the crystal.

#### short-name

type string false [":"] false Short name defining the hexagonal crystal type.

#### space-group

type string false [] false Hermann-Mauguin designation for the space group associated with the symmetry of the crystal (e.g. Immm, Fm-3m, P6_3/mmc).

#### wyckoff-coordinates

type float false [":" 3] false Coordinates of the unique Wyckoff sites used in the fully symmetry-reduced description of the crystal, given as fractions of the lattice vectors. The order of elements in this array must correspond to the order of the entries listed in 'wyckoff-species' and 'wyckoff-multiplicity-and-letter'.

#### wyckoff-multiplicity-and-letter

type string false [":"] false Multiplicity and standard letter of the unique Wyckoff sites used in the fully symmetry-reduced description of the crystal (e.g. 4a, 2b). Note that the sum of the Wyckoff multiplicities should equal the total number of elements in 'basis-atom-coordinates'. The order of elements in this array must correspond to the order of the entries listed in 'wyckoff-species' and 'wyckoff-coordinates'.

#### wyckoff-species

type string false [":"] false The element symbol of the atomic species of the unique Wyckoff sites used in the fully symmetry-reduced description of the crystal. The order of the entries must correspond to the order of the entries in 'wyckoff-multiplicity-and-letter' and 'wyckoff-coordinates'.

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