The NextGen model grid was calculated from to (in steps of 100-) for (in steps of 0.5) and metallicities of (in
steps of 0.5). We use the recent solar abundances given in Table 5 of
[Jaschek & Jaschek(1995)Jaschek and Jaschek]. The changes in the abundances compared to the previous
[Anders & Grevesse(1989)Anders and Grevesse] data are in general small, with the exception of the
iron abundance which changed from 7.67 to 7.53. The grid contains a
total of 2142 models in this range of parameters (the complete NextGen
grid includes 3026 models). In all models, convection is treated in
the mixing length approximation with the mixing length set to unity. We
will discuss the model grid for lower effective temperatures, the VLMS to
Brown Dwarf range of spectral class M, in a separate paper. For effective
temperatures higher than 7000- NLTE effects become important,
so LTE models at higher effective temperature will become increasingly
unrealistic. In cooler models, NLTE effects are important for individual
atomic lines of, e.g., Ti I [Hauschildt et al.(1997b)Hauschildt, Allard, Alexander, and
Baron], for effective temperatures
below about but NLTE does not have significant effects on the
low resolution spectra or the structure of these models. Therefore, we
include a few representative NLTE models (for )in the model grid presented here. A full NLTE grid (with the complete
set of NLTE species available in `PHOENIX`) is currently being constructed
and will be discussed in a later paper (Hauschildt et al, in preparation).

[Aufdenberg et al.(1997a)Aufdenberg, Hauschildt, Shore, and
Baron,Aufdenberg et al.(1997b)Aufdenberg, Hauschildt, Sankrit, and
Baron] have shown that for effective temperatures higher
than about the combined effects of line blanketing and *
spherical geometry* are of crucial importance for main sequence stars with
. In this parameter range, plane parallel models do *
not* deliver enough EUV flux compared to spherical models or observed
EUV spectra. However, for effective temperatures below about the use of the plane parallel approximation in the model construction for
does not result in significant differences to spherical
models. Therefore, we have used the plane parallel geometry to calculate
the present grid. A grid of NLTE spherical model atmospheres for OB
main sequence stars is currently being constructed and will be discussed
in a separate paper (Aufdenberg et al, in preparation). For effective
temperatures lower than about the effects of dust formation
and/or dust opacity become important. This significantly changes the
physics of the model atmospheres and the formation of the spectrum,
therefore, we will discuss these models in a separate paper (Allard et al,
in preparation).

The synthetic spectra and the model structures are available via
anonymous FTP from `ftp://calvin.physast.uga.edu/pub/NextGen` or
via the WWW URL `http://dilbert.physast.uga.edu/yeti` and
constitute about 560 MB of data. For each model, the model structure
(in the form of the `PHOENIX` output file of the last model iteration)
and the synthetic low resolution spectra (directly the result
of the model iterations) are available. The model fluxes are given
as tables of in erg/s/cm^{2}/cm versus wavelength in Å to make comparisons with observed spectra and other model calculations
easier. The spectra are given on an semi-regular wavelength grid with
about 23,000 wavelength points from to cm, the actual
wavelength grid depends on the model.