The spin-orbit ZORA (SO-ZORA) calculations were performed with the Amsterdam Density Functional module (ADF) of the Amsterdam Modeling Suite (AMS). ZORA adapted DZP, TZP, TZ2P and QZ4P Slater-type orbital basis sets were applied in combination with the PBE0 and B3LYP functionals for both geometry optimizations and vibrational frequency calculations. A spherical Gaussian nuclear charge distribution model 62 was applied.