Dictionaries allow CML to be understood by machines. Much of physical science is managed through the dictionary mechanism. We find terms and units relating to a aspect of science (such as heat of formation, melting point, point group) and create entries for these items in a dictionary.
The entries can consist of just a unique id (within the dictionary's namespace) and some human-understandable definition but we strongly encourage more information to be given. For instance: what are the units, are there upper and lower bounds, what is the type of the data (string, integer, float etc).
Different programs sometimes produce data with the same label but a different interpretation; does
density mean electron density or physical density? Therefore each computational chemistry code
will have its own dictionary and then the community can then decide to group particular concepts together
into a higher-level common dictionary (in this case, the compchem dictionary).
- Fundamental Chemistry Concepts
- Chemical Naming Conventions
- Chemical Formula Conventions
- SI Units
- Non-SI Units