Macromodel—an integrated software system for modeling organic and bioorganic molecules using molecular mechanics

An integrated molecular modeling system for designing and studying organic and bioorganic molecules and their molecular complexes using molecular mechanics is described. The graphically controlled, atom‐based system allows the construction, display and manipulation of molecules and complexes having as many as 10,000 atoms and provides interactive, state‐of‐the‐art molecular mechanics on any subset of up to 1,000 atoms. The system semiautomates the graphical construction and analysis of complex structures ranging from polycyclic organic molecules to biopolymers to mixed molecular complexes. We have placed emphasis on providing effective searches of conformational space by a number of different methods and on highly optimized molecular mechanics energy calculations using widely used force fields which are supplied as external files. Little experience is required to operate the system effectively and even novices can use it to carry out sophisticated modeling operations. The software has been designed to run on Digital Equipment Corporation VAX computers interfaced to a variety of graphics devices ranging from inexpensive monochrome terminals to the sophisticated graphics displays of the Evans & Sutherland PS300 series.