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energy-and-crystal-structure-vs-hydrostatic-pressure-relation

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).	energy-and-crystal-structure-vs-hydrostatic-pressure-relation
Property Definition ID The full Property Definition identifier using the Tag URI scheme.	tag:staff@noreply.openkim.org,2025-08-09:property/energy-and-crystal-structure-vs-hydrostatic-pressure-relation
Title A brief one-sentence description of this Property Definition.	Energy and crystal structure as a function of hydrostatic pressure for an arbitrary crystal
Description A description about this Property Definition.	Energy and crystal structure as a function of hydrostatic pressure for an arbitrary crystal. It is expected that the values reported are computed under load boundary conditions and not displacement boundary conditions. This means, for example, that in a noncubic crystal, simply isotropically expanding and shrinking the crystal would not be an acceptable way to compute this property except for cubic crystals. The crystal structure is expressed as an AFLOW prototype label and its corresponding free parameters. The crystal must not transform away from the symmetry specified in this property at any of the reported pressure-energy-structure points. Because of this, only a single prototype label is reported. However, because both the internal and unit cell free parameters may change, they are reported as arrays, with values for each pressure step.
Contributor The user or organization who initially contributed this Property Definition.	ilia
Maintainer The user or organization who currently maintains this Property Definition.	ilia
Creation date The date the Property Definition was "minted", based on its Tag URI.	2025-08-09
Content on GitHub The following content may be available on GitHub: Property Definition (an EDN file containing the Property Definition Keys listed below); Physics Validator (a script provided by the user for validating that an instance of the Property is physically valid); Property Documentation Wiki (the contents of the Wiki displayed at the bottom of this page).	Property Definition Physics Validator Property Documentation Wiki

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Property Definition Keys

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a

type	float
has-unit	true
extent	[":"]
required	true
description	The 'a' lattice constant of the crystal structure as defined by the AFLOW standard. Each element of this array corresponds to the state of this crystal under hydrostatic loading reported in the corresponding element of the 'pressure' array. Relative values of other lattice parameters (if present) are given in the 'parameter-values' key.

binding-potential-energy-per-atom

type	float
has-unit	true
extent	[":"]
required	true
description	Binding potential energy per atom of the crystal defined as follows: \Delta \bar{V}_{atom} = ( V(A_{N_A}B_{N_B}...) - [N_A V_{isolated}(A) + N_B V_{isolated}(B) + ...] )/(N_A + N_B ...), where \Delta \bar{V}_{atom} is the binding energy per atom, V(A_{N_A}B_{N_B}...) is the energy of (any) unit cell, V_{isolated}(X) is the energy of an isolated particle of species X, and N_X is the number of atoms of species X in the (same) unit cell. Each element of this array corresponds to the state of this crystal under hydrostatic loading reported in the corresponding element of the 'pressure' array.

binding-potential-energy-per-formula

type	float
has-unit	true
extent	[":"]
required	true
description	This variable has the same definition as 'binding-potential-energy-per-atom' except that the energy is normalized per chemical formula instead of per atom, i.e. \Delta \bar{V}_{formula} = \Delta \bar{V}_{atom} N_{formula}, where N_{formula} is the number of atoms in the reduced stoichiometric formula, i.e. the sum of indices in the first section of the prototype-label. Each element of this array corresponds to the state of this crystal under hydrostatic loading reported in the corresponding element of the 'pressure' array.

mass-density

type	float
has-unit	true
extent	[":"]
required	true
description	The mass per unit volume of the crystal structure. Each element of this array corresponds to the state of this crystal under hydrostatic loading reported in the corresponding element of the 'pressure' array.

pressure

type	float
has-unit	true
extent	[":"]
required	true
description	The applied hydrostatic pressure at each point in the run.

prototype-label

type	string
has-unit	false
extent	[]
required	true
description	Prototype label (not including an enumeration suffix) as defined by the AFLOW standard (e.g. 'A_tI4_141_a') for the structure. It is expected that the alphabetically lowest of all equivalent labels is chosen. This prototype label must apply to every point in the pressure scan. If the crystal transforms away from this prototype label during one or more points in the pressure scan, those points should not be reported.

stoichiometric-species

type	string
has-unit	false
extent	[":"]
required	true
description	Element symbols corresponding to the atom types in the stoichiometric formula which appears at the start of the prototype label (e.g. ['Mo','S'] for the AB2 stoichiometric formula, means that the 'A' atom is 'Mo' and the 'B' atom is 'S' for the MoS_2 structure).

volume-per-atom

type	float
has-unit	true
extent	[":"]
required	true
description	The volume of the unit cell divided by the number of atoms in the unit cell. Each element of this array corresponds to the state of this crystal under hydrostatic loading reported in the corresponding element of the 'pressure' array.

volume-per-formula

type	float
has-unit	true
extent	[":"]
required	true
description	The volume of the unit cell divided by the number of atoms in the unit cell, multiplied by the number of atoms in the reduced stoichiometric formula, i.e. the sum of indices in the first section of the prototype-label. Each element of this array corresponds to the state of this crystal under hydrostatic loading reported in the corresponding element of the 'pressure' array.

a-vs-pressure-curve

type	file
has-unit	false
extent	[]
required	false
description	The 'a' lattice parameter vs pressure curve.

alpha-vs-pressure-curve

type	file
has-unit	false
extent	[]
required	false
description	The 'alpha' lattice parameter vs pressure curve.

b-over-a-vs-pressure-curve

type	file
has-unit	false
extent	[]
required	false
description	The 'b/a' lattice parameter vs pressure curve.

beta-vs-pressure-curve

type	file
has-unit	false
extent	[]
required	false
description	The 'beta' lattice parameter vs pressure curve.

binding-potential-energy-per-atom-vs-pressure-curve

type	file
has-unit	false
extent	[]
required	false
description	The binding potential energy per atom vs pressure curve.

c-over-a-vs-pressure-curve

type	file
has-unit	false
extent	[]
required	false
description	The 'c/a' lattice parameter vs pressure curve.

coordinates-file

type	file
has-unit	false
extent	[":"]
required	false
description	Files containing the atomic configuration including information such as the species, x,y,z coordinates of each particle, and periodicity data. This configuration is the primitive unit cell of the crystal according to the cell choice defined in M. J. Mehl et al., Comput. Mater. Sci. 136, S1 (2017). Each element of this array corresponds to the state of this crystal under hydrostatic loading reported in the corresponding element of the 'pressure' array.

coordinates-file-conventional

type	file
has-unit	false
extent	[":"]
required	false
description	Files containing the atomic configuration including information such as the species, x,y,z coordinates of each particle, and periodicity data. This configuration is the conventional unit cell of the crystal according to the cell choice defined in M. J. Mehl et al., Comput. Mater. Sci. 136, S1 (2017). Each element of this array corresponds to the state of this crystal under hydrostatic loading reported in the corresponding element of the 'pressure' array.

crystal-genome-source-structure-id

type	string
has-unit	false
extent	[":" ":"]
required	false
description	The identifiers (ID) of the Crystal Genome (CG) structures for which the property (test result and instance) containing this key was computed. Each element is the KIM ID of an OpenKIM Reference Data item that served as the initial configuration before it was relaxed or equilibrated with an interatomic model. Each row corresponds to a structure in the test, i.e. a test computing a property of a single crystal will only have one row, while something like a transformation between two pre-determined crystals would have two rows, and so on. Within each row, there may be multiple columns in the case when multiple initial structures converged to a single final structure during this test or one of its upstream dependencies. Because KIM Property values must be regular arrays, rows will be padded with empty strings to match the longest row.

density-vs-pressure-curve

type	file
has-unit	false
extent	[]
required	false
description	The mass density vs pressure curve.

gamma-vs-pressure-curve

type	file
has-unit	false
extent	[]
required	false
description	The 'gamma' lattice parameter vs pressure curve.

library-prototype-label

type	string
has-unit	false
extent	[]
required	false
description	The AFLOW library prototype, if any, matching the structure. Prototypes in the AFLOW library are associated with common short names used by the materials community. The library prototype includes an integer enumeration suffix defined by the AFLOW standard when there are multiple parameter values associated with the structure (e.g. 'A_tI4_141_a-001' for 'betaSn'). Because these prototype labels are named according to their original material's conventional chemical formula, they may differ from the 'prototype-label' key, which is expected to be standardized to have the alphabetically lowest possible of all equivalent labels. This corresponds to the zero-pressure nominal structure.

parameter-names

type	string
has-unit	false
extent	[":"]
required	false
description	Names of the parameters other than 'a', if present, corresponding to this AFLOW prototype. These can include lattice parameters from the set {'b/a','c/a','alpha','beta','gamma'} (for the conventional crystal structure defined by lattice parameters a, b, and c and angles alpha, beta, gamma), and coordinates of Wyckoff positions that have a degree of variability labeled as 'x', 'y' and 'z*' where the asterisk represents an integer as defined by the AFLOW standard.

parameter-values

type	float
has-unit	false
extent	[":" ":"]
required	false
description	Values for the parameters listed in 'parameter-names'. Note that all parameters are dimensionless. The first index of this array corresponds to the state of this crystal under hydrostatic loading reported in the corresponding element of the 'pressure' array. The second index corresponds to the 'parameter-names'.

short-name

type	string
has-unit	false
extent	[":"]
required	false
description	Commonly used name associated with the 'library-prototype-label' key according to the AFLOW prototype library (e.g. 'Face-Centered Cubic' or 'Molybdenite'). This corresponds to the zero-pressure nominal structure.

volume-per-atom-vs-pressure-curve

type	file
has-unit	false
extent	[]
required	false
description	The volume per atom vs pressure curve.

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