SINGLE CORRECTION FUNCTION FOR COMPUTING RETARDED VAN-DER-WAALS ATTRACTION

Due to the inherent complexity of the general Lifshitz theory, the Ham aker-De Boer approach is still used in computing the van der Waals att ractive force in systems with macrobodies of complex shapes. To accoun t for the retardation of force computed by this approach, the London e quation has in the past been modified by introducing correction functi ons. However, the functions proposed in the past are either piece-wise in nature or valid for a restricted range of separation distances, ma king it difficult to carry out the necessary integrations in cases inv olving complex macrobodies. In this paper, a single correction functio n is proposed. First, the correction function is shown to represent th e retardation effect reasonably wed by comparing the proposed function with those proposed in the past. Then, the retarded van der Waals ene rgy is computed for nine different systems involving mica, quartz, pyr ophyllite, water, polystyrene, and air for the case of two semi-infini te parallel plates separated by a medium. Experimental data found in t he literature on the dielectric frequency spectra are utilized. The re sults are compared with those computed by the general Lifshitz theory and are shown to agree reasonably well. (C) 1995 Academic Press, Inc.