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Workbook Page Hamaker Dash


Creates and Maintains a Database of Materials for Calculating Hamaker Coefficients.

The Hamaker database display (above) shows optical spectrum (interband transition strength or Imaginary part of Dielectric constant), nvis (visual index of refraction), dispersion spectrum, and file comments.

Hamaker Analysis - Full spectral calculations of Hamaker constants.

Experimentally determined interband transition strengths are used to directly derive the London dispersion spectra. Spectral difference functions of the London dispersion spectra lead to direct determination of the Hamaker constants. The Hamaker constants may be calulated in either nonretarded or retarded formulations.

Hamaker constants represent the London Dispersion Force of the van der Waals attraction between two materials. Because London Dispersion Forces arise from the interaction between fluctuating dipoles whose frequencies lie in the optical and UV regions of the spectrum, Hamaker constants may be calculated from the complex dielectric constants measured in the optical/UV portions of the spectrum.

The Hamaker program uses an experimentally determined dielectric constant or interband transition strength. The input data are measured in the ultraviolet and vacuum ultraviolet spectral ranges, and the abscissa are assumed to be eV.

The Hamaker program calculates the London Dispersion spectrum for each input spectrum.

Both the original spectral data, and the corresponding Dispersion spectra, are stored in a database. The database also contains the memo (comments) associated with the original data, and the parameters used in creating the London Dispersion spectra.

Using the London Dispersion spectra, the program will calculate Hamaker constants for 3-layer thin films, for 5-layer thin films, or for an arbitrary number of layers.

The Hamaker constants are written into a log file for future reference.

References for methods used

Non-Dispersive Hamaker Constant:

B. W. Ninham, V. A. Parsegian, `Van de Waals Forces Across Triple-Layer Films', J. Chemical Physics, 52, 4578-87, (1970).

Creation of London Dispersion Spectrum:

D. B. Hough, L. R. White, `The Calculation of Hamaker Constants from Lifshitz Theory with Application to Wetting Phenomena', Advances in Colloid and Interface Science, 14, 3-41, (1980).

Details of Calculations Used in Hamaker program:

R. H. French, R. M. Cannon, L. K. DeNoyer, Y.-M. Chiang, "Full Spectral Calculation of Non-Retarded Hamaker Constants for Ceramic Systems from Interband Transition Strengths", Solid State Ionics, 75, 13-33, (1995). 

See Also

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