Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Eigenvalues and density of states

  1. Mar 15, 2010 #1
    Hi guys

    I have an analytical expression f(x) for my density of states, and I have plottet this. Now, I also have a complete list of my Hamiltonians eigenvalues.

    When I make a histogram of these eigenvalues, I thought that I should get an exact (non-continuous) copy of my plot of f(x). They have the same form, but they are not to scale, i.e. f(x) has a maximum at ~100, while the histogram has a maximum at ~60.

    Is there an error somewhere, or am I wrong to expect that they should be "exact" copies?
     
  2. jcsd
  3. Mar 15, 2010 #2
    I am not sure whether i am correct!
    some scale factor for eigenvaues or for DOS?
    Also check with units of y-axis (i often get these errors when i convert meV to cm-1)
    or your data is convoluted already?
     
    Last edited: Mar 15, 2010
  4. Mar 15, 2010 #3
    The units are the same (I have checked).

    So you believe they should be the same?
     
  5. Mar 19, 2010 #4
    The units of a numerical histogram depend on the bin size chosen. Are you remembering to divide by the width of the bin?
     
  6. Mar 20, 2010 #5
    Isn't a histogram unit-less?
     
    Last edited: Mar 20, 2010
  7. Mar 20, 2010 #6
    Yes, a histogram is unitless. That's why you need to divide by the bin size to get it in units of 1/energy (or 1/energy/volume, if that's what you're dealing with).
     
  8. Mar 21, 2010 #7
    I see. Thanks - I'll play around with it to see if it works. Thanks.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook