# Example: ESR g-tensor, A-tensor, perturbative spin-orbit coupling: HgF¶

Download ESR_HgF_2der.run

This example calculates the ESR g-tensor and A-tensor for HgF. In this example first spin-orbit coupling is taken into account perturbatively.

Note that an all-electron calculation is carried out. This is relevant for the computation of the A-tensor, the nuclear magnetic dipole hyperfine interaction, where an accurate value of the spin-polarization density at the nucleus is important. For the g-tensor this plays a minor role. However, for the g-tensor calculation that includes spin-orbit coupling perturbatively, all electron basis sets are necessary.

In the first example the module nmr calculates the g-tensor (subkey GFACTORS) using spin-orbit coupling and the external magnetic field as perturbation.

$ADFBIN/adf << eor Atoms Hg 0.0 0.0 0.0 F 0.0 0.0 2.804 End Unrestricted Symmetry NoSym Charge 0 1 Basis Type TZ2P Core None End usespcode XC GGA PBE End BeckeGrid Quality verygood End Relativistic Scalar ZORA SCF Iterations 500 Converge 1e-7 1e-7 END SAVE TAPE21 TAPE10 end input eor$ADFBIN/nmr << eor
nmr
gfactors
u1k best
out iso tens
end
end input
eor


In the second example the module cpl calculates the A-tensor (key HYPERFINE) using spin-orbit coupling and the nuclear magnetic field as perturbation. Note that one needs to set the SCF convergence criterium to a small value. For an accurate calculation of the A-tensor one needs a very large basis set in the core region (especially tight s-functions), especially for heavy nuclei. If one has such a large basis set in the core region, one can also see an effect of using a finite size of the nucleus instead of a point nucleus. Such large basis sets can be found for some elements in $ADFRESOURCES/ZORA/jcpl, which are basis sets especially designed for ESR A-tensor and NMR spin-spin coupling calculations. $ADFBIN/adf << eor
Atoms
Hg        0.0 0.0 0.0
F         0.0 0.0 2.804
End
Unrestricted
Symmetry NoSym
Charge 0 1
Basis
Hg ZORA/jcpl/Hg
F  ZORA/jcpl/F
End
usespcode
XC
GGA PBE
End
BeckeGrid
Quality verygood
End
NuclearModel Gaussian
Relativistic Scalar ZORA
SCF
Iterations 500
Converge 1e-7 1e-7
END
end input

\$ADFBIN/cpl << eor
gga
hyperfine
atoms 1 2 :: calculates A-tensor for atom 1 and 2, input order
SCF Converge 1e-7
end
end input
eor