QUAD EFG: Difference between revisions
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The {{TAG|QUAD_EFG}}-tag specifies the nuclear quadrupole moment in millibarns for each atomic species, in the same | The {{TAG|QUAD_EFG}}-tag specifies the nuclear quadrupole moment in millibarns for each atomic species, in the same | ||
order as in the {{FILE|POTCAR}} file. The output ''C''<sub>q</sub> is in MHz. An online compilation of nuclear quadrupole moments can be found [http://www.chem.helsinki.fi/~pyykko/Q2008.pdf here] or in Ref.<ref name="pyykko:molphys:08"/>. | order as in the {{FILE|POTCAR}} file. The output ''C''<sub>q</sub> is in MHz. An online compilation of nuclear quadrupole moments can be found [http://www.chem.helsinki.fi/~pyykko/Q2008.pdf here] or in Ref.<ref name="pyykko:molphys:08"/> (updated numbers in Ref.<ref name="pyykko:molphys:17"/>). | ||
Suppose a solid contains Al, C and Si, than the {{TAG|QUAD_EFG}}-tag could read: | Suppose a solid contains Al, C and Si, than the {{TAG|QUAD_EFG}}-tag could read: | ||
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<references> | <references> | ||
<ref name="pyykko:molphys:08">[http://dx.doi.org/10.1080/00268970802018367 P. Pyykkö, Mol. Phys. 106, 1965 (2008).]</ref> | <ref name="pyykko:molphys:08">[http://dx.doi.org/10.1080/00268970802018367 P. Pyykkö, Mol. Phys. 106, 1965 (2008).]</ref> | ||
<ref name="pyykko:molphys:17">[https://doi.org/10.1080/00268976.2018.1426131 P. Pyykkö, Mol. Phys. 116, 1328 (2017).]</ref> | |||
</references> | </references> | ||
---- | ---- | ||
[[Category:INCAR]][[Category:NMR]][[Category:Electric Field Gradient]] | [[Category:INCAR]][[Category:NMR]][[Category:Electric Field Gradient]] | ||
Revision as of 16:47, 11 January 2022
QUAD_EFG = [real array]
Default: QUAD_EFG = NTYP*1.0
Description: nuclear quadrupole moment (in millbarn) for the atomic types on the POTCAR file.
Setting the QUAD_EFG-tag allows the conversion of the Vzz (see LEFG) values into the Cq often encountered in NMR literature. The conversion formula is as follows (Q is the element and isotope specific quadrupole moment):
The QUAD_EFG-tag specifies the nuclear quadrupole moment in millibarns for each atomic species, in the same order as in the POTCAR file. The output Cq is in MHz. An online compilation of nuclear quadrupole moments can be found here or in Ref.[1] (updated numbers in Ref.[2]).
Suppose a solid contains Al, C and Si, than the QUAD_EFG-tag could read:
QUAD_EFG = 146.6 33.27 0
27Al is the stable isotope of Al with a natural abundance of 100% and Q=146.6. The stable isotopes 12C and 13C are not quadrupolar nuclei, however, the radioactive 11C is. It has Q=33.27. For Si it is pointless to calculate a Cq: again all stable isotopes have I≤1/2. No moments are known for the other isotopes.
Beware: several definitions of are used in the NMR community.
Beware: for heavy nuclei inaccuracies are to be expected because of an incomplete treatement of relativistic effects.