Evaluation of the Constant Wavenumber Cutoff Parameter for Modeling van der Waals Energy

We examine the assumption that the wavenumber cutoff is constant for two parallel plates separated by a third material independent of which of the substances are interacting or forming the intervening medium. We take experimental values of interfacial tension from the literature to calculate wavenumber cutoffs for system configurations of decane, water, and air, and we find that these wavenumber cutoffs are not constant. The interaction energy of each system is plotted as a function of separation distance to compare the divergent Lifshitz, the constant wavenumber, and the system-specific wavenumber models.