One advantage of the Kim-Kim-Suzuki model is that the interfacial energy is independent of the bulk phase free energies, and can be found analytically from the model parameters. Using Eq. (52) from Ref. [1], for a 1D equilibrium interface,
$$ \sigma = \frac{\epsilon \sqrt{w}}{3\sqrt{2}} $$where $\sigma$ is the interfacial energy, $\epsilon^2$ is the gradient energy coefficient, and $w$ is the free energy barrier height.
In the example kks_example_noflux.i, a flat interface between a bulk solid phase with $c_S^e = 0.9$ and a bulk liquid phase with $c_L^e = 0.1$ is equilibrated. In this case, $\epsilon^2 = 1$ and $w=1$. Calculate $\sigma$:
In [1]:
from math import sqrt
eps_sq = 1.0
w = 1
sigma = sqrt(eps_sq)*sqrt(w)/3/sqrt(2)
Display $\sigma$:
In [2]:
sigma
Out[2]: