Korotin S. NLTE synthesis of atomic spectra for the chemical composition determination of the Galactic disc and halo stars

Thesis contains the results of 40 scientific publications that represent materials of investigations of chemical abundances for some elements in stellar atmospheres obtained with the help of thermodynamically non-equilibrium spectral synthesis. Some methods were elaborated which enable one to perform spectral synthesis that takes into account the deviations from LTE (Local Thermodynamical Equilibrium), as well as parameter determination for some atoms and ions (N I, Mg I, Al I, S I, K I, Ca I і Ca II, Sr II, Ba II). Program code MULTI was modified in order to take into account more adequately opacity sources in the stellar atmospheres while performing spectral synthesis. Using this code and created atomic models, the abundances in some samples of the stars were derived. The stars of those samples belong to the various Galactic populations and have different ages. Analysis of elemental abundances in the NLTE approximation was carried out for more than 1000 stars. For the great majority of those stars such determination was performed for the first time. Obtained results can be used in the future studies, as well as for the testing of the theoretical models of the Galactic chemical and dynamical evolution.