Using the fully compressible convection code by Nordlund & Stein
aake:comp-phys (see also bob:santa-barbara, bob:santa-barbara)
we simulate the near-surface convection in a small box,
with 
mesh points on a uniform
x/y-grid and a z-grid
aimed at resolving the temperature structure.
The zero point of z is at 
, with 20% of the box
above z=0, and covering about 13 pressure scale heights in all.
Radiative transfer is computed in detail in 3 dimensions
for 
and at greater optical
depths the diffusion approximation is used.
We use the opacities of
Gustafsson et al. gus:modgrid, with the corresponding opacity
distribution functions (ODF). The so-called MHD equation of state
(e.g. mhd2, mhd2) is used to be
consistent with the envelope models mentioned below, and because it has proven
very good in tests for the sun.