Modeling Electron Paramagnetic Resonance (EPR) with ADF

Electron Paramagnetic Resonance (EPR), also known as Electron Spin Resonance (ESR) is a spectrocopic technique used to probe the structure of paramagnetic compounds. ADF can calculate the two major phenomena that give rise to an EPR/ESR spectrum:

• The g-tensor, which reflects the Zeeman interaction between the (effective) electronic spin of a paramagnetic molecule and an external magnetic field
• The A-tensor, which reflects the nuclear magnetic dipole hyperfine interaction between unpaired electrons and nuclear spin

In addition ADF can calculate

• The Q-tensor, which reflects the nuclear electric quadrupole interaction between a nucleus, with nuclear spin I≥1, and all other charges (ENDOR spectroscopy)
• The D-tensor, which reflects the zero field splitting (ZFS) of the sublevels of an electronic state with S≥1, ADF only calculates the part due to spin-orbit coupling

Benefits include:

• mostly first order properties, thus easy to calculate
• Relativistic effects (ZORA and spin-orbit coupling) can be included
• Code is parallelized
• All electron basis sets for all elements

Links

ADF User Documentation: ESR g-tensor, A-tensor, Q-tensor, ZFS
ADF-GUI: spectroscopic properties
Examples: ESR
References: ESR g-tensor, ESR A-tensor
Related: nuclear quadrupole interaction (ESR Q-tensor)