Indirect correlation function

$\gamma (r)$ is the indirect (or series or chain) correlation function, given by

$\gamma (r)\equiv h(r)-c(r)$.

where Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle h(r)} is the total correlation function, and Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle c(r)} is the direct correlation function.