However, the scope of reactions we can compute accurately is disappointingly narrow. First, accurate first-principles kinetics is mostly confined today to light elements, both for reasons of computational cost, and because the transition metals and lanthanides have low-lying electronic states which reduce the accuracy of single-determinant methods such as CCSD(T) that work so well for organic molecules. The heavy elements introduce additional challenges (relativistic effects, spin-orbit coupling). Supercomputers are advancing rapidly, and many researchers are working to improve quantum chemistry methods for transition metals, so hopefully this major limitation will be resolved in the coming decade.