Abstract
A tremendous increase in computing capacity 1ias allowed us to solve the radiative transfer equation at several thousand frequency points during the iterative solution of the classic model atmosphere problem, and to construct a much more detailed and realistic sampling of the opacity than in earlier models. V,T the harmonic mean and straight mean enable a very fast computation of the model structure, the errors in such simple opacity treatments may be bigger than the errors due to neglect of all improvements in the physics included in computations of model atmospheres of cool stars during the last 25 years! Yet the most simple harmonic mean sampling method the Rosseland mean is often still used to compute boundary conditions for evolutionary models of cool stars. Statistical transformation of measured straight mean absorption coefficients into individual lines, followed by careful sampling, has been a considerable improvement over the direct use of the straight absorption coefficient in the construction of model atmospheres. Key words: OPACITIES - STARS: ATMOSPHERES
