# Accurate and efficient relativistic DFT with ZORA

The zeroth order regular approximation (ZORA) to the Dirac equation accurately and efficiently treats relativistic effects in chemistry. ZORA can be applied with spin-orbit coupling or as scalar correction only.

## Features of ZORA in ADF

• Spin-orbit coupling can be included self-consistently or perturbatively
• Perturbative spin-orbit coupling:
• spin-orbit coupling matrix elements
• singlet and triplet contributions for spin-orbit coupled states
• All electron relativistic basis sets for all elements
• Available for most spectroscopic properties
• Include relativistic effects on structure and reactivity
• Bounded from below, and convergent for Coulombic potential (as opposed to the diverging Pauli Hamiltonian)
• Scaled spinor energies exactly equal Dirac energies for H-like systems