#! /bin/sh


# Example shows an unrestricted B3LYP calculation. In this case ADF also
# calculates the hyperfine interactions at H, P, and O nuclei (keyword ESR).

# The 'RIHartreeFock%DependencyThreshold' key is set to 1E-4. 
# One should check that the results remain reliable if one uses a smaller value
# for the DependencyThreshold key.


AMS_JOBNAME=TZ2P $AMSBIN/ams <<eor
System
  atoms
     O   1.492  0.000  0.000
     P   0.000  0.000  0.000
     H  -0.600 -0.650  1.100
     H  -0.600 -0.650 -1.100
  end
end

Task SinglePoint

Engine ADF
  title hfs H2PO B3LYP TZ2P
  esr
  end
  basis
    core None
    type TZ2P
  end
  numericalquality good
  rihartreefock
    dependencythreshold 1E-4
    quality Normal
  end
  spinpolarization 1
  unrestricted
  xc
    hybrid B3LYP
  end
EndEngine
eor



# For the hyperfine interactions it is important to use all-electron basis sets
# on the interesting nuclei. One can get more accurate results if one uses a
# larger basis set, like the QZ4P basis set, which is present in the
# $AMSRESOURCES/ADF/ZORA directory. 


AMS_JOBNAME=QZ4P $AMSBIN/ams <<eor
System
  atoms
     O   1.492  0.000  0.000
     P   0.000  0.000  0.000
     H  -0.600 -0.650  1.100
     H  -0.600 -0.650 -1.100
  end
end

Task SinglePoint

Engine ADF
  title hfs H2PO B3LYP QZ4P
  esr
  end
  basis
    core None
    type ZORA/QZ4P
  end
  numericalquality good
  rihartreefock
    dependencythreshold 1E-4
    quality Normal
  end
  spinpolarization 1
  unrestricted
  xc
    hybrid B3LYP
  end
EndEngine
eor

# The QZ4P results for the isotropic value of the A-tensor are approximately:
# -24.61 MHz for 17O, 957.33 MHz for 31P, and 110.83 MHz for 1H.

# You may want to compare the results with previous B3LYP results by N. R.
# Brinkmann and I. Carmichael, J. Phys. Chem. A (2004), 108, 9390-9399, which
# give for the Isotropic Fermi Contact Couplings (MHz) for the 2 A' State of H2
# PO using B3LYP, with an aug-cc-pCVQZ basis set: -24.24 MHz for 17O, 963.33
# MHz for 31P, and 111.51 MHz for 1H.