In molecular physics, the Hamaker constant (denoted $A$ ; named for H. C. Hamaker) is a physical constant that can be defined for a van der Waals (vdW) body–body interaction:

A=\pi ^{2}C\rho _{1}\rho _{2},

where $ρ 1, ρ 2$ are the number densities of the two interacting kinds of particles, and $C$ is the London coefficient in the particle–particle pair interaction.^[1]^[2] The magnitude of this constant reflects the strength of the vdW-force between two particles, or between a particle and a substrate.^[1]

The Hamaker constant provides the means to determine the interaction parameter $C$ from the vdW-pair potential,

w(r)={\frac {-C}{r^{6))}.

Hamaker's method and the associated Hamaker constant ignores the influence of an intervening medium between the two particles of interaction. In 1956 Lifshitz developed a description of the vdW energy but with consideration of the dielectric properties of this intervening medium (often a continuous phase).^[3]

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 $1/r^{6};$ this is called the retarded regime, and the result is a Casimir–Polder force.

References

^ ^a ^b Hamaker, H. C. (1937). "The London – van der Waals attraction between spherical particles". Physica. 4 (10): 1058–1072. Bibcode:1937Phy.....4.1058H. doi:10.1016/S0031-8914(37)80203-7.
^ Seung-woo Lee and Wolfgang M. Sigmund (23 May 2002). "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. 204 (1–3): 43–50. doi:10.1016/S0927-7757(01)01118-9.
^ Lifshitz, E.M. (1956). "The Theory of Molecular Attractive Forces between Solids". Soviet Journal of Experimental and Theoretical Physics. 2: 73–83.

v t e Branches of chemistry
Glossary of chemical formulae List of biomolecules List of inorganic compounds Periodic table
Analytical	Instrumental chemistry Electroanalytical methods Spectroscopy IR Raman UV-Vis NMR Mass spectrometry EI ICP MALDI Separation process Chromatography GC HPLC Crystallography Characterization Titration Wet chemistry Calorimetry Elemental analysis
Theoretical	Quantum chemistry Computational chemistry Mathematical chemistry Molecular modelling Molecular mechanics Molecular dynamics Molecular geometry VSEPR theory
Physical	Electrochemistry Spectroelectrochemistry Photoelectrochemistry Thermochemistry Chemical thermodynamics Surface science Interface and colloid science Micromeritics Cryochemistry Sonochemistry Structural chemistry Chemical physics Molecular physics Femtochemistry Chemical kinetics Spectroscopy Photochemistry Spin chemistry Microwave chemistry Equilibrium chemistry Mechanochemistry
Inorganic	Coordination chemistry Magnetochemistry Organometallic chemistry Organolanthanide chemistry Cluster chemistry Solid-state chemistry Ceramic chemistry
Organic	Stereochemistry Alkane stereochemistry Physical organic chemistry Organic reactions Organic synthesis Retrosynthetic analysis Enantioselective synthesis Total synthesis / Semisynthesis Fullerene chemistry Polymer chemistry Petrochemistry Dynamic covalent chemistry
Biological	Biochemistry Molecular biology Cell biology Chemical biology Bioorthogonal chemistry Medicinal chemistry Pharmacology Clinical chemistry Neurochemistry Bioorganic chemistry Bioorganometallic chemistry Bioinorganic chemistry Biophysical chemistry
Interdisciplinarity	Nuclear chemistry Radiochemistry Radiation chemistry Actinide chemistry Cosmochemistry / Astrochemistry / Stellar chemistry Geochemistry Biogeochemistry Photogeochemistry Environmental chemistry Atmospheric chemistry Ocean chemistry Clay chemistry Carbochemistry Food chemistry Carbohydrate chemistry Food physical chemistry Agricultural chemistry Soil chemistry Chemistry education Amateur chemistry General chemistry Clandestine chemistry Forensic chemistry Forensic toxicology Post-mortem chemistry Nanochemistry Supramolecular chemistry Chemical synthesis Green chemistry Click chemistry Combinatorial chemistry Biosynthesis Chemical engineering Stoichiometry Materials science Metallurgy Ceramic engineering Polymer science
See also	History of chemistry Nobel Prize in Chemistry Timeline of chemistry of element discoveries "The central science" Chemical reaction Catalysis Chemical element Chemical compound Atom Molecule Ion Chemical substance Chemical bond Alchemy Quantum mechanics
Category Commons Portal WikiProject

See also

References