Example: B3LYP: H2PO¶
Example shows an unrestricted B3LYP calculation. In this case ADF also calculates the hyperfine interactions at H, P, and O nuclei (keyword ESR).
The ‘DEPENDENCY’ key is set to 1e-4. Note that for hybrids and Hartree-Fock the dependency key is always set. The default value in that case is 4e-3. By explicitly setting the ‘DEPENDENCY’ key we can use a lower value, which is possible in this case. One should check that the results remain reliable if one uses a smaller value for the ‘DEPENDENCY’ key.
$ADFBIN/adf << eor Title hfs H2PO B3LYP TZ2P 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 xc hybrid B3LYP end Basis Type TZ2P Core None End dependency bas=1e-4 BeckeGrid Quality good End ZlmFit Quality good End esr end unrestricted charge 0 1 end input 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 $ADFRESOURCES/ZORA directory. The Basis key should then be:
Basis Type ZORA/QZ4P Core None End
The QZ4P results for the isotropic value of the A-tensor are approximately: -24.61 MHz for 17 O, 957.33 MHz for 31 P, and 110.83 MHz for 1 H.
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 17 O, 963.33 MHz for 31 P, and 111.51 MHz for 1 H.