As computers became more powerful and accessible (see also the Moore law), the 1970s and 1980s saw a significant expansion in computational (and computer) chemistry. Software packages capable of performing semi-empirical and ab initio calculations became widespread, enabling chemists to predict molecular geometries, electronic structures, and reactivity with increasing accuracy, for example, with the density functional theory (DFT). During this decade, E. J. Corey's retrosynthetic analyses, Ivar Ugi's chemical computer analysis (in particular for multicomponent reactions), Johann Gasteiger's Neural Networks, and the Harvard ChemDraw project emerged. This period also marked the beginning of molecular dynamics simulations, allowing for the exploration of the behavior of molecules in motion.