Total correlation function

$h(1,2)$ is the total correlation function, given by

$h(1,2)\equiv g(r_{12})-1$,

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 g(r)} is the pair distribution function.