My specific research is mainly based on two-dimensional ultra-thin structures. Their structural, magnetic, electronic, vibrational, and elastic properties are studied by means of first-principles calculations based on Density Functional Theory (DFT). Specific to vibrational properties of ultra-thin materials, we investigate the phononic characteristics and Raman spectrum of the material in order to have information about its structural phases. For the mechanical properties of a material, we analyze the strain-stress behavior of the material in order to investigate its linear and non-linear elastic properties. Electronic properties are analyzed in terms of the electronic band dispersions, effective masses of electrons and holes, and the atomic orbitals based band decomposed charge densities.