SCM: Examples

VO: collinear approximation, ESR g-tensor, A-tensor, Q-tensor

Sample directory: adf/VO_collinear/

The ESR parameters of VO are calculated with the collinear approximation for unrestricted Spin-Orbit coupled calculations. In this example the VO-molecule has three unpaired electrons.

You calculate Electron Spin Resonance properties with the keywords ESR and QTENS. ESR is a block-type key and is used to compute the G-tensor or the Nuclear Magnetic Dipole Hyperfine interaction. QTENS is a simple key and invokes the computation of the Nuclear Electric Quadrupole Hyperfine interaction.

Proper usage of the key ESR requires that you do one of the following:

(a) A Spin-Orbit calculation, spin-restricted, with exactly one unpaired electron, or
(b) A Spin-Orbit calculation, spin-unrestricted in the collinear approximation, or
(c) No Spin-Orbit terms and spin-unrestricted.

In case (a) and (b) you obtain the G-tensor. In case (b) and (c) you get the Magnetic Dipole Hyperfine interaction.

Note: in case (a) the program also prints a Magnetic Dipole Hyperfine interaction data, but these have then been computed without the terms from the spin-density at the nucleus.
Note: in case (b) and (c) one can have more than one unpaired electron.
Note: in case (b) one has to use symmetry NOSYM.

Two calculations are performed:

Scalar relativistic spin-unrestricted
Spin-Orbit relativistic spin-unrestricted collinear

After the preliminary calculations (DIRAC, to get the relativistic TAPE12 file with relativistic potentials, and the Create runs), we first calculate the Dipole Hyperfine interaction: a spin-unrestricted calculation without Spin-Orbit coupling.

Note that one has to use ALLPOINTS in the calculation for a linear molecule to get results for the nuclear magnetic dipole hyperfine interaction.

$ADFBIN/adf << eor
Atoms
 V 0 0 0
 O 0 0 1.589
End

XC
 GGA Becke Perdew
End

esr
end
qtens

allpoints
unrestricted
charge 0 3

Relativistic  Scalar ZORA
CorePotentials t12.rel  &
 V 1
 O 2
End

integration 5

Fragments
 V t21.V
 O t21.O
End
End input
eor

Then a spin-orbit coupled spin-unrestricted calculation is performed using the collinear approximation. Note that symmetry NOSYM is used.

$ADFBIN/adf << eor
Atoms
 V 0 0 0
 O 0 0 1.589
End

XC
 GGA Becke Perdew
End

esr
end
qtens

symmetry nosym
unrestricted
collinear

Relativistic  Spinorbit ZORA
CorePotentials t12.rel  &
 V 1
 O 2
End

integration 5

Fragments
 V t21.V
 O t21.O
End
End input
eor

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