The connection between self-interaction and static correlation: a random phase approximation perspective

Semi-local density functional theory suggests a connection between static correlation and self-interaction. It is difficult to make such a connection from the wave function theory perspective, since few wave function methods permit self-interaction error. However, the random phase approximation for ground-state correlation, which has a wave function derivation, does include self-interaction in its direct (Hartree) variant. This variant also describes left-right correlation. The self-interaction can be removed by means of second-order screened exchange; however, this also has negative consequences for the description of static correlation. This paper discusses the connection between the two concepts (static correlation and self-interaction) from the perspective provided by the random phase approximation.