Hello, Here [1] I've posted an article describing my efforts integrating MMTK and PyQuante. Feel free to comment. Footnotes: [1] http://www.compchem.kiev.ua/index.php/2006/05/how-to-create-pyquante-forcefield-for-mmtk-part-1/ -- Andrey V Khavryuchenko Software Development Company http://www.kds.com.ua/