SIMBAD references

We describe a new method for computing opacity distribution functions (ODFs) for model atmosphere calculations. The method is tailored to model the atmospheres of individual stars on a modern workstation. Our goal is the computation of model atmospheres for stars with abundances significantly different from the solar or scaled solar composition typically used for grid calculations. As a consistency test, we show that the new procedure is able to reproduce the ODFs and existing model atmospheres for solar abundances, and we describe models for stars with peculiar abundances. We demonstrate that while mild chemical peculiarities can be well represented by scaled solar models, the extreme cases result in a very different atmospheric structure with no analogs in scaled solar grids. Such a structure influences the emerging spectrum as is clearly seen both in the observed flux distribution and in the line ratios that are much better represented by the new models.