Difference between revisions of "Dipole moment"

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(1A x 1 e = 4.8D, a convenient rule)
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For molecular systems, it is customarily given in units of Debyes, after the physicist [[Peter J. W. Debye]].
 
For molecular systems, it is customarily given in units of Debyes, after the physicist [[Peter J. W. Debye]].
In SI units, <math>1</math>D equals approximately <math>3.33564\times 10^{-30}</math> Coulomb-meter (exactly <math>10^{-21}</math>C m<math>^2</math>/s divided by <math>c</math>, the speed of light in vacuum). Conversely, 1 C m = <math>2.9979 10^{29}</math>D.
+
In SI units, <math>1</math>D equals approximately <math>3.33564\times 10^{-30}</math> Coulomb-meter (exactly <math>10^{-21}</math>C m<math>^2</math>/s divided by <math>c</math>, the speed of light in vacuum). Conversely, 1 C m = <math>2.9979 10^{29}</math>D. This is unit is convenient for molecular systems since 1<math>\AA \times 1 e=4.803</math>D.

Revision as of 11:27, 26 May 2008

The electric dipole moment is a measure of polarity. It is the second term in a multipole expansion of a field (the first one being the monopole, or Coulombic, term.) Its definition, for a system of point charges, is \mathbf{p} = \sum_{i=1}^N \, q_i \, \mathbf{r}_i.

For molecular systems, it is customarily given in units of Debyes, after the physicist Peter J. W. Debye. In SI units, 1D equals approximately 3.33564\times 10^{-30} Coulomb-meter (exactly 10^{-21}C m^2/s divided by c, the speed of light in vacuum). Conversely, 1 C m = 2.9979 10^{29}D. This is unit is convenient for molecular systems since 1\AA \times 1 e=4.803D.