van der Waals interaction energy and disjoining pressure at small separation

Area of Science:

• Physical Chemistry
• Surface Science
• Condensed Matter Physics

Background:

• Van der Waals (vdW) forces are crucial in interfacial phenomena.
• The divergence of vdW energy as separation approaches zero poses a theoretical challenge.
• Existing models often attribute this to atomic overlap, which is insufficient.

Purpose of the Study:

• To identify the true origin of the van der Waals energy divergence.
• To develop a model that resolves the divergence and respects thermodynamic constraints.
• To compare new findings with established models.

Main Methods:

• Investigated the role of finite atomic size and overlap.
• Incorporated wavelength dependence of dielectric response functions within Lifshitz theory.
• Derived expressions for vdW energy and disjoining pressure.

Main Results:

• Finite atomic size does not fully explain the divergence.
• Wavelength dependence of dielectric functions is key to resolving the divergence.
• The new model satisfies thermodynamic constraints, removing the L-->0 divergence.

Conclusions:

• The origin of vdW energy divergence is not atomic overlap but a limitation in older models.
• Lifshitz theory, accounting for dielectric properties, provides a robust framework.
• The derived model offers a thermodynamically consistent description of vdW interactions.