# Example: ESR g-tensor, A-tensor, Q-tensor, D-tensor: HfV¶

```
#!/bin/sh
# For the ESR g-tensor and D-tensor (zero-field splitting, ZFS) the effect of
# spin-orbit coupling is important. For the ESR A-tensor and Q-tensor (EFG)
# spin-orbit coupling is less important.
# In this example first spin-orbit coupling is taken into account
# perturbatively. Next spin-orbit coupling is taken into account self-
# consistent, using the COLLINEAR keyword.
# 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 ADF calculation the A-tensor (block key ESR) is calculated
# without the effect of spin-orbit coupling included. The zero-field splitting
# (key ZFS) is calculated by including spin-orbit coupling perturbatively.
AMS_JOBNAME=HfV $AMSBIN/ams <<eor
System
atoms
Hf 0.0 0.0 0.0
V 0.0 0.0 2.033
end
end
Task SinglePoint
Engine ADF
beckegrid
quality good
end
esr
end
basis
core None
type TZ2P
end
qtens
relativity
level scalar
formalism ZORA
end
save TAPE21 TAPE10
spinpolarization 3
symmetry NoSym
unrestricted
zfs
EndEngine
eor
# In the next calculation the module nmr calculates the g-tensor (subkey
# GFACTORS) using spin-orbit coupling and the external magnetic field as
# perturbation.
$AMSBIN/nmr <<eor
adffile HfV.results/adf.rkf
tape10file HfV.results/TAPE10
nmr
gfactors
u1k best
out iso tens
end
eor
rm logfile TAPE15
# The module cpl can calculate 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 criterion to a small value.
$AMSBIN/cpl <<eor
adffile HfV.results/adf.rkf
tape10file HfV.results/TAPE10
hyperfine
atoms 1 2 :: calculates A-tensor for atom 1 and 2, input order
SCF Converge=1e-7
end
eor
rm logfile
# ADF can calculate the g-tensor and A-tensor (block key ESR) using only the
# nuclear or external magnetic field as perturbation, since spin-orbit coupling
# can be taken into account self-consistently. However, in this case, degenerate
# perturbation theory is used. The collinear approximation is used (and symmetry
# NOSYM) to account for spin-polarization effects.
AMS_JOBNAME=HfV_SO $AMSBIN/ams <<eor
System
atoms
Hf 0.0 0.0 0.0
V 0.0 0.0 2.033
end
end
Task SinglePoint
Engine ADF
beckegrid
quality good
end
esr
end
basis
core None
type TZ2P
end
qtens
relativity
level spin-orbit
formalism ZORA
spinorbitmagnetization collinear
end
symmetry NoSym
unrestricted
EndEngine
eor
```