The supramolecular structure class serves as the central element within the module, holding information about the overall code structure. It encompasses the subclasses new_template, metal_site, and patcher, as well as their associated coordination and topology files. Core functionalities include extraction of metal sites from the coordinate file, identification of suitable template from the database and execution of template parametrization. For each metal site identified in the input, a metal_site class is generated, storing the metal index and the corresponding template. Pre-parametrized templates are stored in a dedicated subdirectory within metallicious (in Gromacs topology format). In cases where the template is absent, a new_template class is created, containing all information necessary to parametrize the new metal site (truncated coordinate file, metal name, charge, multiplicity, LJ parameters, and ligands charges). Lastly, the patcher class combines all the metal_site classes with input structure and topology to produce the two output files. metallicious can be executed either via a command line or imported as a Python script (Figure ). The tool requires the following input information: For new templates, users can also include parametrization of improper dihedral formed by metal and bound aromatic molecules, which is turned off by default (See SI §S4.1). This can be done by specifying the improper_metal option. Additionally, several truncation schemes of templates are available to simplify parametrization, which are also turned off by default. A full description of the input is provided in Table .