The IMPACT molecular mechanics program is a comprehensive tool for simulating molecular systems, including proteins, nucleic acids, and organic molecules. It incorporates advanced computational techniques for molecular mechanics, such as fixed-charge and polarizable force fields, and provides specialized modules like Glide for high-throughput docking and QSite for quantum mechanics/molecular mechanics simulations. The program is designed to handle a wide range of molecular systems, including pharmaceutically relevant organic molecules, and supports both explicit and implicit solvent models. IMPACT includes a variety of conformational sampling algorithms and is integrated with the Maestro graphical user interface, which simplifies the setup and execution of simulations. The program's core technologies include force field development, implicit solvation models, and parallel molecular dynamics algorithms. Recent developments in IMPACT focus on improving the accuracy and efficiency of molecular simulations, with a particular emphasis on expanding the coverage of organic compounds and ligands. The program also incorporates the Fast Multipole Method for efficient calculation of long-range electrostatic interactions and advanced solvation models for accurate representation of solvent effects. Overall, IMPACT is a powerful tool for molecular simulations in structural biology and drug discovery.The IMPACT molecular mechanics program is a comprehensive tool for simulating molecular systems, including proteins, nucleic acids, and organic molecules. It incorporates advanced computational techniques for molecular mechanics, such as fixed-charge and polarizable force fields, and provides specialized modules like Glide for high-throughput docking and QSite for quantum mechanics/molecular mechanics simulations. The program is designed to handle a wide range of molecular systems, including pharmaceutically relevant organic molecules, and supports both explicit and implicit solvent models. IMPACT includes a variety of conformational sampling algorithms and is integrated with the Maestro graphical user interface, which simplifies the setup and execution of simulations. The program's core technologies include force field development, implicit solvation models, and parallel molecular dynamics algorithms. Recent developments in IMPACT focus on improving the accuracy and efficiency of molecular simulations, with a particular emphasis on expanding the coverage of organic compounds and ligands. The program also incorporates the Fast Multipole Method for efficient calculation of long-range electrostatic interactions and advanced solvation models for accurate representation of solvent effects. Overall, IMPACT is a powerful tool for molecular simulations in structural biology and drug discovery.