Sample directory: adf/ESR_TiF3/
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.
Five calculations are performed:
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.
$ADFBIN/adf << eor title TiF3 relativistic open shell unrestricted noprint sfo,frag,functions DEFINE RTIF = 1.780 RY = RTIF*SQRT(3)/2 END esr end qtens atoms Ti 0 0 0 F RTIF 0 0 F -RTIF/2 RY 0 F -RTIF/2 -RY 0 end fragments Ti t21.ti F t21.f end xc GGA Becke Perdew end charge 0 1 unrestricted relativistic scalar zora Corepotentials t12.rel & Ti 1 F 2 end end input eor
Then, for the same molecule, we compute the G-tensor in a Spin-Orbit run (spin-restricted).
The here-computed and printed Dipole Hyperfine interaction misses the terms from the spin-density at the nucleus: compare with the outcomes from the first calculation.
In each of the calculations, the QTENS key invokes the computation of the Electric Quadrupole Hyperfine interaction.
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 (and also for the Q-tensor) this plays a minor role, but for reasons of consistency both calculations use the same basis set and (absence of) frozen core.
$ADFBIN/adf << eor title TiF3 relativistic spinorbit open shell restricted noprint sfo,frag,functions DEFINE RTIF = 1.780 RY = RTIF*SQRT(3)/2 END esr end qtens atoms Ti 0 0 0 F RTIF 0 0 F -RTIF/2 RY 0 F -RTIF/2 -RY 0 end fragments Ti t21.ti F t21.f end xc GGA Becke Perdew end relativistic spinorbit zora Corepotentials t12.rel & Ti 1 F 2 end end input eor
Next a scalar relativistic spin-restricted calculation is performed. The TAPE21 of this calculation is saved as a fragment in the next spin-unrestricted calculation, using only 1 SCF iteration, which is a way to get the scalar relativistic spin-restricted open shell result for the magnetic dipole hyperfine interaction.
$ADFBIN/adf << eor title TiF3 scalar relativistic restricted noprint sfo,frag,functions DEFINE RTIF = 1.780 RY = RTIF*SQRT(3)/2 END atoms Ti 0 0 0 F RTIF 0 0 F -RTIF/2 RY 0 F -RTIF/2 -RY 0 end fragments Ti t21.ti F t21.f end xc GGA Becke Perdew end relativistic scalar zora Corepotentials t12.rel & Ti 1 F 2 end end input eor mv TAPE21 t21.TiF3 rm logfile $ADFBIN/adf << eor title TiF3 scalar relativistic open shell restricted noprint sfo,frag,functions DEFINE RTIF = 1.780 RY = RTIF*SQRT(3)/2 END esr end qtens atoms Ti 0 0 0 f=TiF3 F RTIF 0 0 f=TiF3 F -RTIF/2 RY 0 f=TiF3 F -RTIF/2 -RY 0 f=TiF3 end fragments TiF3 t21.TiF3 end xc GGA Becke Perdew end charge 0 1 unrestricted scf iter 0 end relativistic scalar zora Corepotentials t12.rel & Ti 1 F 2 end end input eor
Finally a spin-orbit coupled spin-unrestricted calculation is performed using the collinear approximation. Note that symmetry NOSYM is used.
$ADFBIN/adf << eor title TiF3 relativistic spinorbit open shell unrestricted collinear noprint sfo,frag,functions DEFINE RTIF = 1.780 RY = RTIF*SQRT(3)/2 END esr end qtens symmetry nosym unrestricted collinear atoms Ti 0 0 0 F RTIF 0 0 F -RTIF/2 RY 0 F -RTIF/2 -RY 0 end fragments Ti t21.ti F t21.f end xc GGA Becke Perdew end relativistic spinorbit zora Corepotentials t12.rel & Ti 1 F 2 end end input eor
