  Computation of a grid of self consistent 1D model atmospheres of cool stars,
sub-stellar objects and exoplanets in the effective temperature range 300K to
3000K, including cloud formation, chemical non-equilibrium effects, and stellar
irradiation.
  The models are called MSG, because they are based on an iterative coupling
between three well tested codes, the MARCS stellar atmosphere code, the
StaticWeather cloud formation code and the GGchem chemical equilibrium code. It
includes up-to-date molecular and atomic opacities, cloud formation and
advanced chemical equilibrium calculations, and involves new numerical methods
at low temperatures to allow robust convergence.
  The coupling between the MARCS radiative transfer and GGchem chemical
equilibrium computations has made it possibly effectively to reach convergence
based on electron pressure for the warmer models and gas pressure for the
cooler models, enabling self-consistent modelling of stellar, sub-stellar and
exoplanetary objects in a very wide range of effective temperatures. Here we
describe the basic details of the models, with illustrative examples of cloudy
and irradiated models as well as models based on non-equilibrium chemistry.
  The qualitative changes in the relative abundances of TiO, H2O, CH4, NH3, and
other molecules in our models follow the observationally defined M, L, T (and
Y) sequences, but reveal more complex and depth dependent abundance changes,
and therefore a spectral classification depending on more parameters. The self
consistent coupling to Static-Weather cloud computations, allows detailed
comparison between nucleation and observed relative dimming of different
spectral bands, with advanced applications for new identification methods of
potential exoplanetary biology.
