Knowledge Base

Article ID: 945 - Last Modified:

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. Another option for a quick calculation is to run MOPAC, which is a semiempirical NDDO program and is available from Maestro.

For a more accurate calculation, you can use 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

Back to Search Results

Was this information helpful?

What can we do to improve this information?

To ask a question or get help, please submit a support ticket or email us at
Knowledge Base Search

Type the words or phrases on which you would like to search, or click here to view a list of all
Knowledge Base articles