Article ID: 945 - Last Modified: October 10, 2011
How do I predict a molecule's ionization potential (IP) and electron affinity (EA)?
For a quick calculation, you can use the ionization potential (IP) and electron affinity (EA) descriptors that are reported by QikProp, based on PM3 semiempirical calculations. These properties are not reported in fast mode.
For a more accurate calculation, you canuse Jaguar to run separate ab initio calculations on the neutral and ionic species, and calculate the property from the energy difference. If you want the vertical IP or EA, optimize the geometry of the neutral species and then run a single point calculation on the ion at this geometry. If you want the adiabatic IP or EA, you must optimize the ion geometries as well as the neutral. If you are calculating electron affinities, you should select a basis set that contains diffuse functions (+, ++, or aug-) for both the anion and the neutral atom. You should also use a larger basis set than the default. For the open-shell species, you should use a spin-unrestricted method.
Keywords: properties, QikProp, Jaguar
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