Spherically symmetric model atmospheres for low-mass pre-main-sequence stars with effective temperatures between 2000 and 6800 K

We present a grid of spherically symmetric model atmospheres for young pre-MS stars. This grid spans the parameter range 2000 K less than or equal to T-eff less than or equal to 6800 K and 2.0 less than or equal to log g less than or equal to 3.5 for M = 0.1 M., appropriate for low-mass stars and brown dwarfs. A major improvement is the replacement of TiO and H2O line lists with the newer line list, calculated by the NASA-Ames group, for TiO (about 175 million lines of five isotopes) and for H2O (about 350 million lines in two isotopes). We provide the model structures, spectra, and broadband colors in standard filters in electronic form.