Dipole moment: Difference between revisions
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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 | 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 given by | ||
<math>\mathbf{p} = \sum_{i=1}^N \, q_i \, \mathbf{r}_i.</math> | |||
:<math>\mathbf{p} = \sum_{i=1}^N \, q_i \, \mathbf{r}_i.</math> | |||
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 1Å<math>\times 1 e=4.80320</math>D. | ||
==References== | |||
<references/> | |||
;Related reading | |||
*[http://dx.doi.org/10.1080/00268976.2015.1005191 Carlos Vega "Water: one molecule, two surfaces, one mistake" Molecular Physics '''113''' pp. 1145-1163 (2015)] | |||
[[category: Electrostatics]] | |||
Latest revision as of 12:09, 22 May 2015
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 given by
For molecular systems, it is customarily given in units of Debyes, after the physicist Peter J. W. Debye. In SI units, D equals approximately Coulomb-meter (exactly C m/s divided by , the speed of light in vacuum). Conversely, 1 C m = D. This is unit is convenient for molecular systems since 1ÅD.
References[edit]
- Related reading