Alternating-current relaxation of a rotating metallic particle

Based on a first-principles approach, we establish an alternating-current (AC) relaxation theory for a rotating metallic particle with complex dielectric constant ε_α = ε_α-σ_α/ω₀. Here ε_α is the real part, σ_α the conductivity, ω₀ the angular frequency of an AC electric field, and i=√-1. Our theory yields an accurate interparticle force, which is in good agreement with the existing experiment. The agreement helps to show that the relaxations of two kinds of charges, namely, surface polarized charges (described by ε_α) and free charges (corresponding to σ_α), contribute to the unusually large reduction in the attracting interparticle force. This theory can be adopted to determine the relaxation time of dynamic particles in various fields.