## dislocation-core-energy-cubic-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). dislocation-core-energy-cubic-crystal-npt tag:staff@noreply.openkim.org,2021-02-24:property/dislocation-core-energy-cubic-crystal-npt Dislocation core energy of a cubic crystal at zero temperature and a given stress state The dislocation core energy is a mathematical construct designed to remove the singularity in the stress and strain fields of elasticity theory. The total strain energy is computed relative to the cohesive energy of the ideal crystal, and the core energy is the portion of this energy that is not accounted for by an elastic model. In this property, the dislocation core energy for cubic crystals at zero temperature and a given stress state is reported using three different elastic models: nonsingular, isotropic, and anisotropic. Each of these core energies is computed for a range of dislocation core cutoff radii and is given in units of energy per unit dislocation line length. qyc081025 qyc081025 2021-02-24 Property Definition Physics Validator Property Documentation Wiki
See the KIM Properties Framework for more detailed information.

Jump below to Property Documentation Wiki content

#### Property Definition Keys

Required Optional

#### a

type float true [] true Equilibrium conventional lattice constant of the cubic crystal.

#### 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.

#### burgers-vector-direction

type float false  true The Burgers vector of the dislocation given as a vector of three real numbers relative to the lattice parameter, e.g. [0.5, 0.5, 0] corresponds to a Burgers vectors of [a/2, a/2, 0].

#### cauchy-stress

type float true  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 aligned with the cubic 4-fold axes of the crystal.

#### core-energy-anisotropic

type float true [":"] true The core energy calculated using the classical theory of anisotropic elasticity using a finite dislocation core cutoff radius.

#### core-energy-isotropic

type float true [":"] true The core energy calculated using the classical theory of isotropic elasticity using a finite dislocation core cutoff radius.

#### core-energy-nonsingular

type float true [":"] true The core energy calculated using the (isotropic) nonsingular theory of elasticity. This is computed by spreading the Burgers vector isotropically around the dislocation line in the region defined by the core radius. For reference, see W. Cai, A. Arsenlis, C. R. Weinberger, and V. V. Bulatov, A non-singular continuum theory of dislocations, JMPS 54, 561 (2006).

type float false [":"] true The physical region where atoms present a radically distinct local order with respect to the bulk. This parameter is given in terms of the magnitude of the Burgers vector, e.g. a value of 0.5 defines a core region of radius b/2 where b is the magnitude of the Burgers vector.

#### dislocation-line-direction

type int false  true The crystallographic direction of the dislocation line direction given as a vector of three integers, e.g. [1, 1, 2].

#### slip-plane-miller-indices

type int false  true The vector of Miller indices defining the slip plane of the dislocation, e.g. [1, 1, 1].

#### 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'.

#### relaxed-core-positions

type float true [":" 3] false The [x,y,z] coordinates of each particle after relaxation.

#### short-name

type string false [":"] false Short name defining the cubic 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'.

### Property Documentation Wiki

Wiki is ready to accept new content.