@ARTICLE{rappe,
author  = {A. K. Rapp\'e and C. J. Casewit and K. S. Colwell and W. A. Goddard III and W. M. Skid},
title   = {UFF, a Full Periodic Table Force Field for Molecular Mechanics and Molecular Dynamics Simulations},
journal = "J. Am. Chem. Soc.",
year    = 1992,
volume  = 114,
pages   = 10024 
}