Peak, valley, and intermediate regimes in the lateral van der Waals force

We study the van der Waals (vdW) interaction between a polarizable particle and grounded conducting corrugated surface. For sinusoidal corrugations, one knows that, under action of lateral vdW force, an isotropic is always attracted to nearest corrugation peak, with such behavior called in present paper as peak regime. Here, considering anisotropic particle, making analytical calculations valid beyond proximity force approximation (PFA), we show that attraction not only toward peaks, but, for certain orientations distances from surface, attracts valley (valley regime), or even intermediate point (intermediate regime). also configurations transition regimes vanishes, presence In addition, find these new occur general, periodic nonperiodic surfaces. Moreover, demonstrate similar arise classical neutral polarized rough The description regimes, which are out reach predictions based on PFA, may be relevant better understanding particles surfaces quantum physics, experimental verifications feasible both domains.