Route providing computed piezoelectric data for a material following the methodology discussed by [de Jong *et al.*](https://doi.org/10.1038/sdata.2015.53) Note that piezoelectric data has not been calculated for all materials in the Materials Project database. See the `PiezoDoc` schema for a full list of fields returned by this route.
openapi: 3.1.0
info:
title: Materials Project Defect Tasks Materials Piezoelectric API
description: "\nThe Materials Project API allows anyone to have direct access to current, up-to-date information from the Materials Project database in a structured way.\n\nThis allows for analysis, development of automated tools, machine learning, downloading personal copies of the Materials Project database and more on a large scale.\n\nThe API is offered with the hopes of making Materials Project data more useful to you. We want you to use our data! As such, the API is offered free-of-charge and we support several tools to help you get started.\n\n## API Key\nTo make any request to the Materials Project API, you must use an API key. Your API key is generated for you automatically upon registering with the Materials Project website and is synced with the email you used to register.\n\nRemember to keep your API key safe and to not share it with anyone you do not trust.\n\nIf you are logged in, you can always access your API key from this page or from your [dashboard](https://next-gen.materialsproject.org/dashboard).\n\nIf you intend heavy API usage, you can give us a heads up by sending a message to <heavy.api.use@materialsproject.org>. With the exception of retrieving charge densities, this is not required, but may help us if we see unusual load on our servers.\n\n## Accessing Data\nTo use the API, you have three options:\n\n1. You can use our first-party supported Python client. This is the recommend route. The `mp-api` package containing the client is pip installable.\n\n ```\n pip install mp-api\n ```\n\n The `MPRester` client can be accessed by importing from it. This will ultimately replace the legacy `MPRester` available in pymatgen.\n\n For more details on how to use this, including code examples, please see <https://next-gen.materialsproject.org/api>.\n\n2. You can demo the API interactively on this documentation page. Click the \"Authorize\" button, paste in your API key, and then click the appropriate section to try out a query.\n\n3. Since this is a REST API, and offers a fully-compliant OpenAPI specification, it's possible to use the API with many libraries in many languages and environments, including JavaScript, MATLAB, Mathematica, etc. However, we do not offer first-party support for explaining how to do this, and you will have to follow the specification yourself.\n\n"
version: 0.86.4rc5.dev1+g77c2c1315
x-logo:
url: https://raw.githubusercontent.com/materialsproject/emmet/master/emmet-api/emmet/api/core/assets/mp_logo_small.png
security:
- ApiKeyAuth: []
tags:
- name: Materials Piezoelectric
description: Route providing computed piezoelectric data for a material following the methodology discussed by [de Jong *et al.*](https://doi.org/10.1038/sdata.2015.53) Note that piezoelectric data has not been calculated for all materials in the Materials Project database. See the `PiezoDoc` schema for a full list of fields returned by this route.
externalDocs:
description: For a more detailed description
url: https://docs.materialsproject.org/methodology/piezoelectricity
paths:
/materials/piezoelectric/:
get:
tags:
- Materials Piezoelectric
summary: Get PiezoelectricDoc documents
operationId: search_materials_piezoelectric__get
parameters:
- name: material_ids
in: query
required: false
schema:
anyOf:
- type: string
- type: 'null'
description: Comma-separated list of material_id values to query on
title: Material Ids
description: Comma-separated list of material_id values to query on
- name: piezo_modulus_max
in: query
required: false
schema:
anyOf:
- type: number
- type: 'null'
description: Maximum value for the piezoelectric modulus in C/m².
title: Piezo Modulus Max
description: Maximum value for the piezoelectric modulus in C/m².
- name: piezo_modulus_min
in: query
required: false
schema:
anyOf:
- type: number
- type: 'null'
description: Minimum value for the piezoelectric modulus in C/m².
title: Piezo Modulus Min
description: Minimum value for the piezoelectric modulus in C/m².
- name: _page
in: query
required: false
schema:
type: integer
description: Page number to request (takes precedent over _limit and _skip).
title: ' Page'
description: Page number to request (takes precedent over _limit and _skip).
- name: _per_page
in: query
required: false
schema:
type: integer
description: Number of entries to show per page (takes precedent over _limit and _skip). Limited to 1000.
default: 100
title: ' Per Page'
description: Number of entries to show per page (takes precedent over _limit and _skip). Limited to 1000.
- name: _skip
in: query
required: false
schema:
type: integer
description: Number of entries to skip in the search.
default: 0
title: ' Skip'
description: Number of entries to skip in the search.
- name: _limit
in: query
required: false
schema:
type: integer
description: Max number of entries to return in a single query. Limited to 1000.
default: 100
title: ' Limit'
description: Max number of entries to return in a single query. Limited to 1000.
- name: _fields
in: query
required: false
schema:
type: string
description: 'Fields to project from PiezoelectricDoc as a list of comma separated strings. Fields include: `builder_meta` `nsites` `elements` `nelements` `composition` `composition_reduced` `formula_pretty` `formula_anonymous` `chemsys` `volume` `density` `density_atomic` `symmetry` `material_id` `deprecated` `deprecation_reasons` `last_updated` `origins` `warnings` `structure` `property_name` `total` `ionic` `electronic` `e_ij_max` `max_direction` `strain_for_max`'
title: ' Fields'
description: 'Fields to project from PiezoelectricDoc as a list of comma separated strings. Fields include: `builder_meta` `nsites` `elements` `nelements` `composition` `composition_reduced` `formula_pretty` `formula_anonymous` `chemsys` `volume` `density` `density_atomic` `symmetry` `material_id` `deprecated` `deprecation_reasons` `last_updated` `origins` `warnings` `structure` `property_name` `total` `ionic` `electronic` `e_ij_max` `max_direction` `strain_for_max`'
- name: _all_fields
in: query
required: false
schema:
type: boolean
description: Include all fields.
default: false
title: ' All Fields'
description: Include all fields.
responses:
'200':
description: Search for a PiezoelectricDoc
content:
application/json:
schema:
$ref: '#/components/schemas/Response_PiezoelectricDoc_'
'422':
description: Validation Error
content:
application/json:
schema:
$ref: '#/components/schemas/HTTPValidationError'
components:
schemas:
EmmetMeta:
properties:
emmet_version:
anyOf:
- type: string
- type: 'null'
title: Emmet Version
description: The version of emmet this document was built with.
default: 0.86.4rc4
pymatgen_version:
anyOf:
- type: string
- type: 'null'
title: Pymatgen Version
description: The version of pymatgen this document was built with.
default: 2026.4.16
run_id:
anyOf:
- type: string
- type: 'null'
title: Run Id
description: The run id associated with this data build.
batch_id:
anyOf:
- type: string
- type: 'null'
title: Batch Id
description: Identifier corresponding to the origin of this document's blessed task.
database_version:
anyOf:
- type: string
- type: 'null'
title: Database Version
description: The database version for the built data.
build_date:
anyOf:
- type: string
format: date-time
- type: 'null'
title: Build Date
description: The build date for this document.
license:
anyOf:
- type: string
enum:
- BY-C
- BY-NC
- type: 'null'
title: License
description: License for the data entry.
type: object
title: EmmetMeta
description: Default emmet metadata.
ValidationError:
properties:
loc:
items:
anyOf:
- type: string
- type: integer
type: array
title: Location
msg:
type: string
title: Message
type:
type: string
title: Error Type
input:
title: Input
ctx:
type: object
title: Context
type: object
required:
- loc
- msg
- type
title: ValidationError
PiezoelectricDoc:
properties:
builder_meta:
anyOf:
- $ref: '#/components/schemas/EmmetMeta'
- type: 'null'
description: Builder metadata.
nsites:
anyOf:
- type: integer
- type: 'null'
title: Nsites
description: Total number of sites in the structure.
elements:
anyOf:
- items:
type: string
type: array
- type: 'null'
title: Elements
description: List of elements in the material.
nelements:
anyOf:
- type: integer
- type: 'null'
title: Nelements
description: Number of elements.
composition:
anyOf:
- additionalProperties:
type: number
type: object
- type: 'null'
title: Composition
description: Full composition for the material.
composition_reduced:
anyOf:
- additionalProperties:
type: number
type: object
- type: 'null'
title: Reduced Composition
description: Simplified representation of the composition.
formula_pretty:
anyOf:
- type: string
- type: 'null'
title: Pretty Formula
description: Cleaned representation of the formula.
formula_anonymous:
anyOf:
- type: string
- type: 'null'
title: Anonymous Formula
description: Anonymized representation of the formula.
chemsys:
anyOf:
- type: string
- type: 'null'
title: Chemical System
description: Dash-separated string of elements in the material.
volume:
anyOf:
- type: number
- type: 'null'
title: Volume
description: Total volume for this structure in ų.
density:
anyOf:
- type: number
- type: 'null'
title: Density
description: Density in g/cm³.
density_atomic:
anyOf:
- type: number
- type: 'null'
title: Packing Density
description: The atomic packing density in ų/atom.
symmetry:
anyOf:
- $ref: '#/components/schemas/SymmetryData'
- type: 'null'
description: Symmetry data for this material.
material_id:
anyOf:
- type: string
pattern: ^([A-Za-z]+-)?(\d+)(-[A-Za-z0-9]+)*$
examples:
- mp-3534
- '3453'
- mp-834-Ag
- type: string
examples:
- mp-ft
- task:pqrs
- type: 'null'
title: Material Id
description: 'The Materials Project ID of the material, used as a universal reference across property documents.This comes in the form: mp-******.'
deprecated:
type: boolean
title: Deprecated
description: Whether this property document is deprecated.
default: true
deprecation_reasons:
anyOf:
- items:
type: string
type: array
- type: 'null'
title: Deprecation Reasons
description: List of deprecation tags detailing why this document isn't valid.
last_updated:
type: string
format: date-time
title: Last Updated
description: Timestamp for the most recent calculation update for this property.
origins:
anyOf:
- items:
$ref: '#/components/schemas/PropertyOrigin'
type: array
- type: 'null'
title: Origins
description: Dictionary for tracking the provenance of properties.
warnings:
items:
type: string
type: array
title: Warnings
description: Any warnings related to this property.
default: []
property_name:
type: string
title: Property Name
default: piezoelectric
total:
items:
items:
type: number
type: array
type: array
title: Total
description: Total piezoelectric tensor in C/m²
ionic:
items:
items:
type: number
type: array
type: array
title: Ionic
description: Ionic contribution to piezoelectric tensor in C/m²
electronic:
items:
items:
type: number
type: array
type: array
title: Electronic
description: Electronic contribution to piezoelectric tensor in C/m²
e_ij_max:
type: number
title: E Ij Max
description: Piezoelectric modulus
max_direction:
items:
type: integer
type: array
title: Max Direction
description: Miller direction for maximum piezo response
strain_for_max:
items:
type: number
type: array
title: Strain For Max
description: Normalized strain direction for maximum piezo repsonse
type: object
required:
- total
- ionic
- electronic
- e_ij_max
- max_direction
- strain_for_max
title: PiezoelectricDoc
description: A dielectric package block
Meta:
properties:
api_version:
type: string
title: Api Version
description: A string containing the version of the Materials API implementation, e.g. v0.9.5
default: 0.86.4rc5.dev1+g77c2c1315
time_stamp:
type: string
format: date-time
title: Time Stamp
description: A string containing the date and time at which the query was executed
total_doc:
anyOf:
- type: integer
minimum: 0.0
- type: 'null'
title: Total Doc
description: The total number of documents available for this query
facet:
anyOf:
- additionalProperties: true
type: object
- type: 'null'
title: Facet
description: A dictionary containing the facets available for this query
additionalProperties: true
type: object
title: Meta
description: Meta information for the MAPI Response.
SymmetryData:
properties:
crystal_system:
anyOf:
- type: string
- type: 'null'
title: Crystal System
description: The crystal system for this lattice.
symbol:
anyOf:
- type: string
- type: 'null'
title: Space Group Symbol
description: The spacegroup symbol for the lattice.
hall:
anyOf:
- type: string
- type: 'null'
title: Hall Symbol
description: Hall symbol for the lattice
number:
anyOf:
- type: integer
- type: 'null'
title: Space Group Number
description: The spacegroup number for the lattice.
point_group:
anyOf:
- type: string
- type: 'null'
title: Point Group Symbol
description: The point group for the lattice.
symprec:
anyOf:
- type: number
- type: 'null'
title: Symmetry Finding Precision
description: The precision provided to spglib to determine the symmetry of this structure.
angle_tolerance:
anyOf:
- type: number
- type: 'null'
title: Angle Tolerance
description: Angle tolerance provided to spglib to determine the symmetry of this structure.
version:
anyOf:
- type: string
- type: 'null'
title: spglib version
type: object
title: SymmetryData
description: Defines a symmetry data set for materials documents
Response_PiezoelectricDoc_:
properties:
data:
anyOf:
- items:
$ref: '#/components/schemas/PiezoelectricDoc'
type: array
- type: 'null'
title: Data
description: List of returned data
errors:
anyOf:
- items:
$ref: '#/components/schemas/Error'
type: array
- type: 'null'
title: Errors
description: Any errors on processing this query
meta:
anyOf:
- $ref: '#/components/schemas/Meta'
- type: 'null'
description: Extra information for the query
type: object
title: Response[PiezoelectricDoc]
Error:
properties:
code:
type: integer
title: Code
description: The error code
message:
type: string
title: Message
description: The description of the error
type: object
required:
- code
- message
title: Error
description: Base Error model for General API.
PropertyOrigin:
properties:
name:
type: string
title: Name
description: The property name
task_id:
anyOf:
- type: string
pattern: ^([A-Za-z]+-)?(\d+)(-[A-Za-z0-9]+)*$
examples:
- mp-3534
- '3453'
- mp-834-Ag
- type: string
examples:
- mp-ft
- task:pqrs
title: Task Id
description: The calculation ID this property comes from.
last_updated:
type: string
format: date-time
title: Last Updated
description: The timestamp when this calculation was last updated
type: object
required:
- name
- task_id
title: PropertyOrigin
description: Provenance document for the origin of properties in a material document
HTTPValidationError:
properties:
detail:
items:
$ref: '#/components/schemas/ValidationError'
type: array
title: Detail
type: object
title: HTTPValidationError
securitySchemes:
ApiKeyAuth:
descriptions: MP API key to authorize requests
name: X-API-KEY
in: header
type: apiKey