What is Debye: Definition and 69 Discussions

The debye (symbol: D) (; Dutch: [dəˈbɛiə]) is a CGS unit (a non-SI metric unit) of electric dipole moment named in honour of the physicist Peter J. W. Debye. It is defined as 1×10−18 statcoulomb-centimeters. Historically the debye was defined as the dipole moment resulting from two charges of opposite sign but an equal magnitude of 10−10 statcoulomb (generally called e.s.u. (electrostatic unit) in older literature), which were separated by 1 Ångström. This gave a convenient unit for molecular dipole moments.

Typical dipole moments for simple diatomic molecules are in the range of 0 to 11 D. Symmetric homoatomic species, e.g. chlorine, Cl2, have zero dipole moment, and highly ionic molecular species have a very large dipole moment, e.g. gas-phase potassium bromide, KBr, with a dipole moment of 10.5 D.The debye is still used in atomic physics and chemistry because SI units are inconveniently large. The smallest SI unit of electric dipole moment is the yoctocoulomb-meter, which is roughly 300,000 D. There is currently no satisfactory solution to this problem of notation without resorting to the use of scientific notation.

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  1. L

    What is the debye temperature?

    can someone please tell me what the debye termperature is, in words. why is it important? and is it actually a temperature? thanks
  2. I

    Interpretation of the Debye length

    What exactly is the Debye length? From what I understand, when a charge q>0 is shielded by an electron cloud, then the Debye length is the distance the potential of the charge q falls by 1/e. Is it that simple? Furthermore, how do you go about deriving the expression...
  3. T

    How Does Dimensionality Affect Specific Heat in the Debye Model?

    Homework Statement Consider a linear array of N similar atoms, the separation between nearest neighbours being a. Discuss the specific heat of the system on the basis of the Debye approximation and show that at low temperatures, the specific heat would be expected to be proportional to T...
  4. R

    Deriving Normalized Debye Model: Step-by-Step Guide

    Hi Members, We know that in Debye model, the phonon spectrum is given by g(\omega)=Const.\omega^2. And if we have N atoms and so 3N normal modes..so 3N=integral of g(\omega)d\omega and solving by simple integration rule we get Const. = 9N/(\omega^3_D). Now my problem is how to get it...
  5. S

    Calculate Debye Temperature for Carbon 13

    Homework Statement Carbon 12 has a debye temperature of 2230 K, what is the debye temperature of carbon 13? No data on Debye frequency is provided. Homework Equations This is the problem, the only equations I can find relate the Debye Frequency to the Debye Temperature. \theta_{D}...
  6. A

    What does a high Debye temperature signify?

    What does a high Debye temperature mean? I know it's related to the phonon contribution to heat capacity at low temperatures, but that's about it. Specifically, why is the Debye temperature of copper so much higher than that of lead? (I'm working on this in lab right now and can't find an...
  7. H

    Is there a formula for the temperature dependence of Debye temperature?

    I guess is Debye temperature dependent on temperature? I.e TD(T)? Does anybody know a theoretical formula for temperature dependence of Debye temperature?:confused:
  8. U

    Heat Capacity / Debye Temperature

    Homework Statement We are looking at the molar heat capacity, Cv, of copper over temperatures from 1-300K After plotting the numbers and looking at T from 1-15K, then fitting that to a curve. We have to find what the constants \beta and \gamma are in ... Cv=\gammaT + \betaT_{3} Where...
  9. S

    Specific Heat / Debye Temperature

    Homework Statement At what temperature T does the specific heat of the free electrons become larger than the specific heat of the lattice? Express T in terms of the Debye temperature and the electron concentration. Calculate T for copper (Debye = 343 K). Homework Equations...
  10. H

    Zero-Point Energy of a Debye Solid

    Homework Statement Show that the zero point energy of a Debye solid is: (9/8) N k (Debye Temp) Homework Equations zero point energy = sum of (1/2 w hbar ) over all i The Attempt at a Solution I used the Debye spectrum g(w) = 9N w^2 / w(D)^3, for w < w(D) g(w) = 0 for w>w(D) Then I...
  11. M

    How Can You Calculate Debye Equation Parameters for Curve Fitting?

    Hi, I need to calculate the parameters of the following equation: S = (a + ((b-a)/(1+((2*pi*x)^2*c^2)))) I have the measured data of S and need the parameters a,b and c to get a curve fit in the software for analysis. If someone can help me in this regard or suggest any software that...
  12. T

    Why Are the Results in My PDF Different from the Attached Paper?

    Hi Guyz, Why the results in the paper I've attached aren't like the results I got in my pdf? Please look at the paper in the last line, the second term doesn't correspond to what I calculated, What i calculated is in the pdf file, is it wrong? Why in my work there is exponential terms...
  13. A

    What is R in the Debye Heat Capacity Equation?

    I am currently re-reading an old textbook on thermal physics and they have listed the final result for calculating the Debye Heat Capacity as C =9R(T/ThetaD)^3*Integral((z^4*e^z dz)/(e^z-1)^2, 0-->ThetaD/T) But they fail to mention what the R in this equation is, Could some one please tell...
  14. Clausius2

    Can a Debye Layer Form in Air?

    Just a question: I do know it is possible to have a debye layer in a electrolyte. But is it posible to have a Debye layer in air?. I mean, if I put a single charged particle in air, do I have a layer of ionized air surrounding it??. Thanks.
  15. A

    Calculating Density of Aluminium Using Debye Theory

    I've calculates the density of aluminium using the debye theory. I found The atom density n = 2.24E28 m^-3 at 600k (assumed to be the same as at room temperature). Therefore the density is just the molecular mass m (m(grams) = (79amu / Avogadros number), multiplied by the atom density...
  16. A

    Debye Frequency in Crystal: Exploring Longitudinal Lattice

    in a crystal, when proving the debye frequency, why is the existence of longitudinal lattice ignored? why is there longitudinal lattice in the first place?
  17. N

    Understanding the Debye Length in Plasma Physics

    Can someone explain to me what this is? All we were told in my Physics of Stars module was that for a plasma, L \gg \lambda_{D}, where \lambda_{D} is the Debye length. We were also told that it's an "e-folding distance" for a potential, but that doesn't help to understand it. I'm not...
  18. S

    Debye Potential and Jupiter encounter

    1) It is desired to use an encounter with Jupiter to send a spacecraft on a trajectory which barely escapes the solar system. The spacecraft is launched from Earth onto a trajectory whose aphelion is at Jupiter’ s orbit. Determine how close to the surface of Jupiter the spacecraft must...
  19. D

    Finding the Debye Length for Xenon Ions

    Greetings ! I searched the web and couldn't find it. I wan'na know the Debye length for Xenon ions. Thanks ! :smile: Live long and prosper.
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