In more practical terms a Becke (non-uniform) grid might be more useful (this is also used in DFT calculations), but this exponential need for memory still remains an issue. The first major innovation to solving the Schrödinger equation is the Mean-Field approximation on 1-body wavefunctions, for electrons (Fermions more generally), the Hartree-Fock approximation (when including exchange), as is explained in §C.2. This reduces the memory substantially to: