The project consists in the study and analysis of the chemical information that can be obtained in the presence of an electric quadrupole moment of the nuclei. Such a quadrupole moment indicates a non-spherical charge distribution of the nucleus and will couple to the electric field gradient associated with the other nuclei as well as the electrons of the molecule. Calculations of the electric field gradient combined with experiment allows the extraction of the value of the electric quadrupole moment of the nucleus but also provides information about the electronic structure, notably the bonding situation, in the molecule. We explored this using the so-called Townes–Dailey model in a relativistic framework. The 35Cl isotope was investigated in detail in different molecular environments, but also 238U isotope in the UO_{2}^{2+} was studied, to verify the Townes-Dailey model in systems presenting d and f valence orbitals. The contribution of the different atomic orbitals to the electric field gradient was evaluated using projection analysis, a linear combination of atomic orbitals approach based on the expansion of the molecular orbitals in pre-calculated occupied atomic orbitals of the atom (or site).