The document discusses energy minimization in molecular modeling. It explains that energy minimization aims to find the lowest energy conformation of a molecule by exploring different conformations and determining which has the smallest steric energy. There are local minima, which are relative energy minima within a small region, and global minima, which represent the absolute lowest energy state when considering the entire molecule. Molecular mechanics is preferred over quantum mechanics for energy minimization due to its ability to model larger molecules more accurately. Multiple local minima can be combined to approximate the global minimum for complex molecules with many degrees of freedom.