However, there is overlap between these diagrams and the Olvera de la Cruz approach. There, contributions from the self-site interactions would lead to ring diagrams that include some character of the excluded volume portion by its inclusion in the potential u c,α,γ . This means that there is some overlap with ring-like diagrams in the f 0 part of the expansion in the current case. Thus, these two approaches (including in the RPA versus adding on the Carnahan-Starling result) give rise to two different sets of slightly-overlapping diagrams.