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Thermodynamic equipartition of energy theorem - application to life

  1. Mar 29, 2012 #1
    hi, I'm simulating a system of molecules (water) and in order to pass through a barrier they have to overcome an energy barrier of 4kT. What is the probability of a water molecule passing the barrier or perhaps what is the average energy of a water molecule in my system?

    I know it's 1/2 *kT per each degree of freedom, but how many degrees of freedom do my water molecules have? (I'm simulating at 320K, water molecules are SPC/E).

    Oh, and i also have ions in my system. What is their average energy? 3/2kT?

    Thanks for any insight!
  2. jcsd
  3. Mar 31, 2012 #2
    Did you mean degrees of freedom per water molecule?

    http://www.pha.jhu.edu/~broholm/l37/node5.html [Broken]

    Perhaps you should also take into consideration the pressure and pressure difference in the water?
    Last edited by a moderator: May 5, 2017
  4. Mar 31, 2012 #3


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    It's not that trivial for fluids due to interactions. You can basically look at Maxwell-Boltzman Distribution which deals with something very similar for gases, and you might be able to use it as a rough estimate for water, but don't expect anything particularly good out of it.
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