Using the spin-resolved electronic direct correlation function to estimate the correlation energy of the spin-polarized uniform electron gas

We report a simple ansatz that includes spin-polarization in two different models for the exchange-correlation hole. Both models were originally conceived for the non-polarized uniform electron gas. One of them is based on the electronic direct correlation function, a novel approach to build the long-range behavior of the exchange-correlation hole. This ansatz is shown to work quite well considering the limitations of the original models. Interestingly, the hole based on the direct correlation function provides better results in general. This suggests that it is better to model the electronic direct correlation function than it is to model the hole directly.