MOLCAS manual: 4.5 Input Structure and EMIL Commands MOLCAS has a modular program structure. The easiest way to run calculations is to prepare an input file in which the different programs are executed sequentially when the the module name (&module) is provided. The keywords of module name then follow, with each entry on a separate line or several entries on one line, separated by ;. In addition to specific program module keywords, MOLCAS incorporates certain commands (See section on EMIL Commands.) that allow operations such as looping over the modules, allowing partial execution, changing variables, and substituting certain Unix commands.