Defining new materials

There are two main ways to use a material which is not built in to the Solcore database, which can also be connected. They are:

  1. Downloading and using the database from refractiveindex.info
  2. Providing n and k data, and other parameters, to create_new_material

In order to control where custom materials get saved, you need to tell Solcore where to create and look for new materials by adding some entries to your user configuration file (by default, a hidden folder called .solcore_config.txt in your home directory):

  • Path the refractiveindex.info database will be downloaded to is set under [Others] with flag nk.
  • Path where n and k data will be saved is set under [Others] with flag custom_mats.
  • Path where the file containing parameters of custom materials will be created is set under [Parameters] with flag custom.

The following code snippet sets the location for each of these within a folder called Solcore, which is a sub-directory of your home folder (you could also manually add the correct paths to the config file).

import os
from solcore.config_tools import add_source

home_folder = os.path.expanduser('~')
custom_nk_path = os.path.join(home_folder, 'Solcore/custommats')
nk_db_path = os.path.join(home_folder, 'Solcore/NK.db')
param_path = os.path.join(home_folder, 'Solcore/custom_params.txt')

add_source('Others', 'custom_mats', custom_nk_path)
add_source('Others', 'nk', nk_db_path)
add_source('Parameters', 'custom', param_path)

Adding new materials to the database

solcore.material_system.create_new_material.create_new_material(mat_name, n_source, k_source, parameter_source=None, overwrite=False)[source]

This function adds a new material to Solcore’s material_data folder, so that it can be called like a built-in material. It needs a name for the new material, and source files for the n and k data and other parameters which will be copied into the material_data/Custom folder.

Parameters:
  • mat_name – the name of the new material
  • n_source – path of the n values (txt file, first column wavelength in m, second column n)
  • k_source – path of the n values (txt file, first column wavelength in m, second column k)
Param:

parameter_source: file with list of parameters for the new material

The correct format for the n and k files are tab or space separated text files, with the first column the wavelength in metres and the second column n or k. The file containing other parameters should take

When you add a new material to the database, a new folder will be created for it as a subfolder of the path specified in your (user or default) configuration under the custom_mats path. The n and k data files you provide will be copied into that folder (they are renamed automatically). Any other parameters you supply will be copied into the file specified under the custom path.

Using refractiveindex.info

solcore.absorption_calculator.nk_db.download_db(url=None, interpolation_points=200, confirm=False)[source]

This function downloads the refractiveindex.info database and creates on SQLite database at the path specified in the user config file.

Parameters:
  • url – URL from which the zip archive of the database will be downloaded. Default is “https://refractiveindex.info/download/database/rii-database-2017-09-05.zip”
  • interpolation_points – how many interpolation points to save the data at. Default is 200.
  • confirm – if True, will not ask if you want to download database again even if it has been downloaded previously
Returns:
solcore.absorption_calculator.nk_db.search_db(term='', exact=False)[source]

Search the downloaded SQLite database.

Parameters:
  • term – search term (e.g. the name of a material, or a source).
  • exact – search by exact (True) or approximate (False, default) terms.
Returns:

A list of tuples of with one tuple per database entry matching the search term.

The first entry of each tuple is the pageid of the database entry.

solcore.absorption_calculator.nk_db.nkdb_load_n(pageid)[source]
solcore.absorption_calculator.nk_db.nkdb_load_k(pageid)[source]
solcore.absorption_calculator.nk_db.create_nk_txt(pageid, file, folder='')[source]

This function creates two files called [file]_n.txt and [file]_k.txt (with [file] as specified in the arguments. The format matches that used by create_new_material, with the first column being the wavelength in metres and the second column the n or k values.

Parameters:
  • pageid – pageid (number) of the database entry to be used
  • file – name of the file to be created: the n and k data will be saved separately as

[file]_n.txt and [file]_k.txt :param folder: folder where the files should be saved :return: parameter_source: file with list of other parameters for the new material

Before the first use, you will need to download the database:

from solcore.absorption_calculator download_db
download_db()

download_db takes two (optional) arguments: the URL of the database to be downloaded, (default is the most recent, hardcoded into the function), and how many interpolation points to use when saving the database (default is 200).

The code which is used to download and get data from the refractiveindex.info database is based on code from Hugo Guillen.

You can now directly use materials from the .db file created this way by referencing them via their pageid. To locate which database entry you want to use, you can search the database; the code below searches the database for entries matching ‘Diamond’ and then uses the pageid of the first result to create an instance of this new Diamond material. In general, though, it is a good idea to check explicitly which of the database entries is appropriate (e.g. in terms of the wavelength range, and which type of data is available) rather than simply using the first result.

results = search_db('Diamond')
Diamond = material(name = str(results[0][0]), nk_db = True)()

Adding materials from refractiveindex.info to the database

There is a convenient function, create_nk_txt, to generate the n and k data files needed to add a new material to the Solcore database directly from the downloaded refractiveindex.info database:

results = search_db('Diamond')
create_nk_txt(pageid=results[0][0], file='C_Diamond')
create_new_material(mat_name = 'Diamond', n_source='C_Diamond_n.txt', k_source='C_Diamond_k.txt')

This searches the refractiveindex.info database for entries matching ‘Diamond’, and then creates files with the n and k data from the first matching database entry in the format required by create_new_material.