Re: How to calculate entropy of particles?

On Feb 14, 11:40 pm, Eric Gisse <jowr...@xxxxxxxxx> wrote:
On Feb 14, 9:22 pm, Rick Giuly <rgiuly.gr...@xxxxxxxxx> wrote:

Hello all,

I'm working on a molecular dynamics simulation based on Lennard-Jones
potential. Each particle has a position, a mass, and a velocity.

I know that temperature is the average kinetic energy of all the
particles, so temperature is no problem to calculate.

But, how would you calculate the entropy of the particles?

S = k ln(number of states)
dS = dQ / T



Any help is appreciated.

-Rick Giuly
If replying by email please use: rgiuly at ucsd dot edu

reference:http://en.wikipedia.org/wiki/Lennard-Jones_potential

The problem I have with S = k ln(number of states) is that it seems
like the number of states is nearly infinite, since there are multiple
particles and each can be at any location in space.

dS = dQ / T
This formula tells me something about how the entropy would change
when heat is added but I want to calculate the entropy as a function
of the position and velocity of all the particles at an instant in
time.

So I'm still not sure how to calculate the entropy (as a function of
the position and velocity of all the particles at an instant in time).

-Rick
.

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