Hamaker constant

From Wikipedia, the free encyclopedia
Jump to: navigation, search

The Hamaker constant A can be defined for a Van der Waals (VdW) body-body interaction:

where and are the number of atoms per unit volume in two interacting bodies and C is the coefficient in the particle-particle pair interaction.[1][2] It is named after H. C. Hamaker.

The Hamaker constant provides the means to determine the interaction parameter C from the Van der Waals pair potential, .

Hamaker's method and the associated Hamaker constant ignores the influence of an intervening medium between the two particles of interaction. In the 1950s Lifshitz developed a description of the VdW energy but with consideration of the dielectric properties of this intervening medium (often a continuous phase).

The Van der Waals forces are effective only up to several hundred angstroms. When the interactions are too far apart the dispersion potential decays faster than ; this is called the retarded regime and the result is a Casimir–Polder force.

See also[edit]


  1. ^ Hamaker, H. C. (1937) The London – van der Waals attraction between spherical particles. Physica 4(10), 1058–1072. doi:10.1016/S0031-8914(37)80203-7
  2. ^ Seung-woo Lee and Wolfgang M. Sigmund."AFM study of repulsive Van der Waals forces between Teflon AF thin film and silica or alumina." Colloids and Surfaces A: Physicochemical and Engineering Aspects. Volume 204, Issues 1-3, 23 May 2002, Pages 43–50