One solution to this problem is through range-separation, where the Coulomb operator is split into short-and long-range components, such that the amount of exact exchange varies as a function of inter-electronic distance. Such functionals are called range-separated hybrids (RSHs), and can be constructed to ensure the correct long-range behavior. In addition, these functionals exhibit reduced self-interaction error according to typical measures. It is also possible to further increase the accuracy by including some amount of non-local correlation by introducing a dependence on the virtual (unoccupied) orbitals. Double hybrid functionals achieve this by including a fraction of MP2 correlation; they have received much interest in recent years. The UW12 approximation is a non-local correlation approximation given by 25