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Suppose we have a system at constant . We minimize .
This means we make a line and the curve A(N). We want to minimize the distance between the line and curve we make a tangent. If the curve is above tangent, the point is locally stable, otherwise--unstable.
In -T space we have a coexistence curve:
In N-T space we have a coexistence region
Why the difference? Because is intensive, and N is extensive variable!
Is there an ending point for coexistence curve?
© 1997 Boris Veytsman and Michael Kotelyanskii