Relativistic effects in molecular structure of s and p-block elements

Relativistic quantum theory is well known since Dirac formulated it in 1928. However, relativistic quantum chemical methods have only been developed in the last two decades. Fully relativistic program codes for atoms and molecules are now available. Such program codes make it feasible for the first time to perform calculations for the heavier elements in the periodic table. For these elements relativistic effects cannot be neglected anymore. For example, spin-orbit coupling becomes similar or even larger in size compared to typical bond energies in trans-actinide compounds. The stability of compounds containing heavy elements can change dramatically due to relativistic effects thus influencing both structure and reactivity.