ATTRACTION AND REPULSION

Gibbs energy of repulsion (between two surfaces)		$G_r$
Gibbs energy of repulsion due to electric effects		$G_{\text{el}}$
Gibbs energy of repulsion per unit area of two parallel plates		$g_r$, $g_{\text{el}}$
Gibbs energy of attraction of two surfaces		$G_a$
Gibbs energy of attraction per unit area of two parallel plates		$g_a$
Van der Waals-London attraction constant between two molecules ( $={\phi}r^6$)		${\lambda}$
(Van der Waals-)Hamaker constant between semi-infinite flat plates, distance $h$ apart ($n$ = number of molecules per unit volume) ( $=-g_a{\cdot}12{\pi}h^2 = {\pi}^2n^2{\lambda}$)		$A_H$
Retarded van der Waals constant between two molecules ( $=-{\phi}r^7$)		${\beta}$
Retarded van der Waals constant between semi-infinite flat plates, distance $h$ apart ( $=-3g_ah^3 = (1/10){\pi}n^2{\beta}$)		$B$
Total Gibbs energy of interaction (and per unit area of two parallel plates)		$G_t(g_t)$
Disjoining pressure ( $=-\mathrm{d}g_t/\mathrm{d}h$)		${\Pi}_d$