A Guide to Equivariance Theory for Chemists
Introduction Suppose we want to simulate the motion of atoms in a molecule or a material. In principle, the forces on the nuclei come from quantum mechanics. In practice, this is hard because the full electron-nuclear Schrodinger equation is far too expensive to solve at every molecular dynamics step. The usual starting point is the Born-Oppenheimer approximation. Since nuclei are much heavier and move much more slowly than electrons, we treat the nuclear positions as fixed while solving the electronic problem. Let ...