The Material class

Overview

Similarly to Adsorbate, a Material is a helper wrapper class around pyGAPS concepts. The user might want to store details about adsorbent materials they use. The information can range from date of synthesis, material density, etc. For this case, pyGAPS provides the Material class.

The isotherm required property of material is used to create or connect a BaseIsotherm instance to a Material. Each time an isotherm is created, pyGAPS looks in the main material list (pygaps.MATERIAL_LIST) for an instance with the same name. This list is populated as import-time with materials stored in the internal database. The user can also add their own material to the list, or upload it to the database for permanent storage. If the material does not exist in pygaps.MATERIAL_LIST, pyGAPS will create a new instance for the isotherm.

Any calculations/conversions then rely on the Material for providing parameters such as material molar mass and density.

Note

For a complete list of methods and individual descriptions look at the Material reference.

Creating a Material

To create an instance of a Material, parameters must contain a value for the material name, with anything else being optional. Some are recognised as special properties (density, ...), while other parameters passed are saved as well in an internal dictionary called properties.

An example of how to create a material:

my_material = pygaps.Material(
    'carbon',                   # Name
    density=1,                  # Recognised
    molar_mass=256,             # Recognised
    batch='X1',                 # User specific
    owner='Test User',          # User specific
    form='powder',              # User specific
    treatment='acid etching'    # User specific
)

To view a summary of the material properties:

my_material.print_info()

Hint

All custom properties are found in the Material.properties dictionary.

my_material.properties["form"]
>> "powder"

Material class methods

The Material class has some specific methods which denote recognised properties:

• Molar mass: molar_mass().

• Density: density().

These are not calculated, just looked up in the properties dictionary.

my_material.molar_mass()
>> 256

Material management

In pyGAPS, materials can be stored in the internal sqlite database. At import-time, the list of all materials is automatically loaded into memory and stored in pygaps.MATERIAL_LIST. The easiest way to retrieve a material from the list is to use the find() class method. It takes the material name as parameter.

carbon = pygaps.Material.find('carbon')

At first the database will be empty. To populate the database with materials, the user should create the materials first and then append them to the list for temporary storage, or upload them to the database for permanent storage.

# To store in the main list
pyGAPS.MATERIAL_LIST.append(my_material)

A useful shorthand is to pass an optional parameter store at creation

# Automatically stored in MATERIAL_LIST
mat = pygaps.Material("MOF", store=True)

Warning

This makes the material available only in the current session. No permanent changes to the materials are made this way.

To permanently store a custom material for later use or make modifications to exiting materials, the user must upload it to the internal database. This can be done as:

import pygaps.parsing as pgp

# To permanently store in the database
pgp.material_to_db(mat_new)

# To store any modifications to an material in the database
pgp.material_to_db(mat_modified, overwrite=True)

For more info, check out the sqlite section of the manual.