Encyclopedia API Tutorial

import requests
import matplotlib.pyplot as plt
# import json
# import os

# ENCYCLOPEDIA API URL
nomad_api_url ="https://encyclopedia-api.nomad-coe.eu/v1.0/materials"

# ENCYCLOPEDIA API Token (this one is valid for the NOMAD summer, no need to use a different one)
api_access_token ="eyJpYXQiOjE1MDQ3MTg2NTAsImFsZyI6IkhTMjU2IiwiZXhwIjoxNTA3MzEwNjUwfQ.eyJpZCI6InRlc3RfdG9rZW4ifQ.hiCIfi0bAW_O6CsMpQaTBzqUhpfu6VguVEudm9HV7Xs"

#### SEARCH EXAMPLES ###

# search for a material by element, Exclusive ON
# Note: this is the search used in order to get working the next steps for this tutorial. If you change
# the search criteria then the rest of this tutorial should be changed as well (calc nr, material nr, ...)
r = requests.post(nomad_api_url, auth=(api_access_token, ''), \
                  json = {"search_by":{"element": "Ag", "exclusive": "1"}})

# search for materials by element, Exclusive OFF
# r = requests.post(nomad_api_url, auth=(api_access_token, ''), \
#                   json = {"search_by":{"element": "Ag", "exclusive": "0"}})

# get the second page of previous results with 5 results per page
# r = requests.post(nomad_api_url, auth=(api_access_token, ''), \
#                   json = {"search_by":{"element": "Ag", "exclusive": "1", "page": 2, "per_page": 5}})

# search for materials using multiple elements
# r = requests.post(nomad_api_url, auth=(api_access_token, ''), \
#                   json = {"search_by":{"element": "Ti,O", "exclusive": "1"}})

# search for materials using formula
# r = requests.post(nomad_api_url, auth=(api_access_token, ''), \
#                   json = {"search_by":{"formula": "Ac2Ag3", "exclusive": "1"}})

# search can be done also by using specific properties in combination with elements/formula
# example: materials containing Ag and having DOS data
# r = requests.post(nomad_api_url, auth=(api_access_token, ''), \
#                   json = {"search_by":{"element": "Ag", "exclusive": "0"}, \
#                          "has_dos": "True"})

# check the status code of the search command
r.status_code

# check the results of our search
content = r.json()

content

# get the total number of results
content['total_results']

# check the number of results by counting the entries in "results" list
len(content['results'])

# let's show the formula, reduced formula and the space_group for each material found
for material in content['results']:
    print("formula:", material['formula'], "reduced formula:", material['formula_reduced'], "space_group: ", material['space_group'])

# let's create a list with the available materials id
id_list =[]
for material in content['results']:
    id_list.append(material['id'])
print(id_list)

# get more properties for a specific material (for example: material_id 714)
material_714 = requests.get(nomad_api_url + "/714", auth=(api_access_token, ''))

material_714.json()

# get all calculations for a specific material (material_id 714)
material_714_calcs = requests.get("https://encyclopedia-api.nomad-coe.eu/v1.0/materials/714/calculations", auth=(api_access_token, ''))

# show the available calculations for our material
calculations = material_714_calcs.json()
calculations

# check how many calculations we have available for this specific material
calculations['total_results']

# get the "id" and the "functional long name" property for the first calculation in our list
calculations['results'][0]['id']
calculations['results'][0]['functional_long_name']

# request a specific property for one calculation, here for example we ask for "density of states" data
r = requests.get("https://encyclopedia-api.nomad-coe.eu/v1.0/materials/714/calculations/249502?property=dos", auth=(api_access_token, ''))

# it is good from time to time to check the status returned by our HTTP request :)
r.status_code

# get only the DOS data from previous request result
dos = r.json()

# show the DOS data
dos

# let's see what kind of data we have there
dos['dos'].keys()

# get only the DOS energies
energies = dos['dos']['dos_energies']

# show the DOS energies
energies

# get the DOS values
values = dos['dos']['dos_values']

# show the DOS values
values

type(values)

# show plots inline in notebook
%matplotlib inline

# rescale the energy values by atomic unit of charge: 1.602176565e-19 (C)
new_energy = [item/1.602176565e-19 for item in energies]

# plotting things
plt.plot(values[0], energies, color="darkorange", linewidth=1.5)