Following this are numerous examples in the state of the art of researchers using techniques typically used for smaller molecular systems to examine solid state systems. Li and co-workers use Fermi's Golden Rule (Equation ) to examine diphenyldibenzofulvene, whereby they diabatisise their electronic states to yield 3.816×10 10 s -1 for S 1 recombination, and 3.429 × 10 10 s -1 for S 2 recombination. As well, a number of other theories, such as the energy gap law and the ShaMan model, are applicable to condensed matter systems, but have not been attempted in the current state of the art due to the computational costs.