The exchange-correlation hole ρXC(r,r+u) describes the reduction in electron density at point r+u due to the presence of an electron at the reference point r. It is of crucial importance for the development of approximations to the exchange-correlation energy EXC[ρ]. There are various tools available to gain insight into ρXC(r,r+u), such as the adiabatic connection [1], density scaling [2], and density functional perturbation theory [3]. Using these means, we develop approximations to ρXC(r,r+u) that build on the correlation factor ansatz, ρXC(r,r+u)= fC(r,r+u) ρX(r,r+u) [4,5]. The correlation factor fC(r,r+u) turns the exchange hole ρX(r,r+u) into the exchange-correlation hole. We discuss the construction of the correlation factor, we show how it can be made self-correlation free and how it can account for strong correlation. Furthermore, we show how to combine density functional perturbation theory with the correlation factor approach by constructing a correlation factor as a function of the coupling strength of the adiabatic connection. References [1] Langreth, Perdew, Solid State Commun. 17, 1425 (1975); Phys. Rev. B 15, 2884 (1977). [2] Levy, Perdew, Phys. Rev. A 32, 2010 (1985). [3] Görling, Levy, Phys. Rev. A 50, 196 (1994). [4] Burke, Perdew, Ernzerhof, IJQC 61, 287 (1997). [5] Precechtelova, Bahmann, Kaupp, Ernzerhof, J. Chem. Phys. 143, 144102 (2015).

The correlation factor model: Generalizations and applications

255th National Meeting (2018)

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