The paper presents analytical expressions for energy gradients in the zeroth order regular approximation (ZORA) to the Dirac equation, used for relativistic effects. The electrostatic shift approximation (ESA) is employed to avoid gauge dependence issues. The study compares the ZORA method with the quasirelativistic Pauli method, highlighting the limitations of the latter. Geometry optimizations and bond dissociation energies for transition metal complexes (W(CO)₆, Os(CO)₅, Pt(CO)₄) are calculated, and basis set effects are investigated. The ZORA ESA method is shown to be more stable and accurate than the ZORA (MP) method, which still suffers from gauge dependence. The paper discusses the implementation of the ZORA ESA method in the ADF program, emphasizing the use of frozen cores and basis set requirements. It also compares results from the ZORA ESA method with those from the quasirelativistic Pauli method, showing that the ZORA ESA method provides more accurate and stable results. The study concludes that the ZORA ESA method is a good compromise between efficiency and accuracy for relativistic calculations.The paper presents analytical expressions for energy gradients in the zeroth order regular approximation (ZORA) to the Dirac equation, used for relativistic effects. The electrostatic shift approximation (ESA) is employed to avoid gauge dependence issues. The study compares the ZORA method with the quasirelativistic Pauli method, highlighting the limitations of the latter. Geometry optimizations and bond dissociation energies for transition metal complexes (W(CO)₆, Os(CO)₅, Pt(CO)₄) are calculated, and basis set effects are investigated. The ZORA ESA method is shown to be more stable and accurate than the ZORA (MP) method, which still suffers from gauge dependence. The paper discusses the implementation of the ZORA ESA method in the ADF program, emphasizing the use of frozen cores and basis set requirements. It also compares results from the ZORA ESA method with those from the quasirelativistic Pauli method, showing that the ZORA ESA method provides more accurate and stable results. The study concludes that the ZORA ESA method is a good compromise between efficiency and accuracy for relativistic calculations.