  Large-scale stellar surveys, such as SDSS-V, 4MOST, WEAVE, and PLATO, require
accurate atmospheric models and synthetic spectra of stars for accurate
analyses of fundamental stellar parameters and chemical abundances. The primary
goal of our work is to develop a new approach to solve radiation-hydrodynamics
(RHD) and generate model stellar spectra in a self-consistent and highly
efficient framework. We build upon the Copenhagen legacy RHD code, the MULTI3D
non-local thermodynamic equilibrium (NLTE) code, and the DISPATCH
high-performance framework. The new approach allows us to calculate 3D RHD
models of stellar atmospheres on timescales of a few thousand CPU hours and to
perform subsequent spectrum synthesis in local thermodynamic equilibrium (LTE)
or NLTE for the desired physical conditions within the parameter space of
FGK-type stars. We compare the 3D RHD solar model with other available models
and validate its performance against solar observations, including the
centre-to-limb variation of intensities and key solar diagnostic lines of H and
Fe. We show that the performance of the new code allows to overcome the main
bottleneck in 3D NLTE spectroscopy and enables calculations of
multi-dimensional grids of synthetic stellar observables for comparison with
modern astronomical observations.
