Example: ESR spin-restricted and spin-unrestricted: TiF3¶

#!/bin/sh


# 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:
# - Scalar relativistic spin-restricted
# - Scalar relativistic open shell spin-restricted
# - Scalar relativistic spin-unrestricted
# - Spin-Orbit relativistic spin-restricted
# - Spin-Orbit relativistic spin-unrestricted collinear

# First a scalar relativistic spin-restricted calculation is performed. The
# results of this calculation are used as a fragment in the next spin-
# unrestricted calculation, using only 0 SCF iterations, which is a way to get
# the scalar relativistic spin-restricted open shell result for the magnetic
# dipole hyperfine interaction.


AMS_JOBNAME=TiF3_SR $AMSBIN/ams <<eor
System
  atoms
     Ti  0      0                  0
     F   1.780  0                  0
     F  -0.89   1.5415252187363007 0
     F  -0.89  -1.5415252187363007 0
  end
end

Task SinglePoint

Engine ADF
  title TiF3  scalar relativistic restricted
  basis
    core None
    type TZ2P
    CreateOutput Yes
  end
  noprint sfo frag functions
  relativity
    level scalar
    formalism ZORA
  end
  xc
    gga Becke Perdew
  end
EndEngine
eor

AMS_JOBNAME=TiF3_SR_0 $AMSBIN/ams <<eor
System
  atoms
     Ti  0      0                  0 adf.f=TiF3
     F   1.780  0                  0 adf.f=TiF3
     F  -0.89   1.5415252187363007 0 adf.f=TiF3
     F  -0.89  -1.5415252187363007 0 adf.f=TiF3
  end
end

Task SinglePoint

Engine ADF
  title TiF3  scalar relativistic open shell restricted
  esr
  end
  fragments
     TiF3 TiF3_SR.results/adf.rkf
  end
  noprint sfo frag functions
  qtens
  relativity
    level scalar
    formalism ZORA
  end
  scf
    iterations 0
  end
  spinpolarization 1
  unrestricted
  xc
    gga Becke Perdew
  end
EndEngine
eor

# Next a spin-unrestricted SCF calculation is performed to get the scalar
# relativistic spin-unrestricted result for the magnetic dipole hyperfine
# interaction.


AMS_JOBNAME=TiF3_SR_unrestricted $AMSBIN/ams <<eor
System
  atoms
     Ti  0      0                  0 adf.f=TiF3
     F   1.780  0                  0 adf.f=TiF3
     F  -0.89   1.5415252187363007 0 adf.f=TiF3
     F  -0.89  -1.5415252187363007 0 adf.f=TiF3
  end
end

Task SinglePoint

Engine ADF
  title TiF3  relativistic open shell unrestricted
  esr
  end
  fragments
     TiF3   TiF3_SR.results/adf.rkf
  end
  noprint sfo frag functions
  qtens
  relativity
    level scalar
    formalism ZORA
  end
  spinpolarization 1
  unrestricted
  xc
    gga Becke Perdew
  end
EndEngine
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.


AMS_JOBNAME=TiF3_SO $AMSBIN/ams <<eor
System
  atoms
     Ti  0      0                  0 adf.f=TiF3
     F   1.780  0                  0 adf.f=TiF3
     F  -0.89   1.5415252187363007 0 adf.f=TiF3
     F  -0.89  -1.5415252187363007 0 adf.f=TiF3
  end
end

Task SinglePoint

Engine ADF
  title TiF3  relativistic spinorbit open shell restricted
  esr
  end
  fragments
     TiF3   TiF3_SR.results/adf.rkf
  end
  noprint sfo frag functions
  qtens
  relativity
    level spin-orbit
    formalism ZORA
  end
  xc
    gga Becke Perdew
  end
EndEngine
eor

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


AMS_JOBNAME=TiF3_SO_unrestricted $AMSBIN/ams <<eor
System
  atoms
     Ti  0      0                  0 adf.f=TiF3
     F   1.780  0                  0 adf.f=TiF3
     F  -0.89   1.5415252187363007 0 adf.f=TiF3
     F  -0.89  -1.5415252187363007 0 adf.f=TiF3
  end
end

Task SinglePoint

Engine ADF
  title TiF3  relativistic spinorbit open shell unrestricted collinear
  esr
  end
  fragments
     TiF3   TiF3_SR.results/adf.rkf
  end
  noprint sfo frag functions
  qtens
  relativity
    level spin-orbit
    formalism ZORA
    spinorbitmagnetization collinear
  end
  symmetry nosym
  unrestricted
  xc
    gga Becke Perdew
  end
EndEngine
eor