  Mixing length theory is the predominant treatment of convection in stellar
models today. Usually described by a single free parameter, alpha, the common
practice is to calibrate it using the properties of the Sun, and apply it to
all other stellar models as well. Asteroseismic data from Kepler and CoRoT
provide precise properties of other stars which can be used to determine alpha
as well, and a recent study of stars in the Kepler field of view found alpha to
vary with metallicity. Interpreting alpha obtained from calibrated stellar
models, however, is complicated by the fact that the value for alpha depends on
the surface boundary condition of the stellar model, or T-tau relation.
Calibrated models that use typical T-tau relations, which are static and
insensitive to chemical composition, do not include the complete effect of
metallicity on alpha. We use 3D radiation-hydrodynamic simulations to extract
metallicity-dependent T-tau relations and use them in calibrated stellar
models. We find the previously reported alpha-metallicity trend to be robust,
and not significantly affected by the surface boundary condition of the stellar
models.
