Thermodynamic equipartition of energy theorem - application to life

[trelek2]

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!

 

[CognitiveNet]

Did you mean degrees of freedom per water molecule?

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

Perhaps you should also take into consideration the pressure and pressure difference in the water?

 

[K^2]

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.