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Does anybody know where to find a database for atomic and molecular energy levels, with the corresponding energy values for each level? It would be needed just for small molecules. I tried the NIST website but it only has the ground state energies.

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    $\begingroup$ It does not get you all orbitals, but the Pitt Quantum Repository contains at least calculated HOMO and LUMO values for over 100,000 molecules. $\endgroup$ – Ben Norris Oct 13 '16 at 19:10
  • $\begingroup$ Hi Ben, I could not find the energy levels on that website. $\endgroup$ – MarkAdams Oct 14 '16 at 14:25
  • $\begingroup$ Go to the site and search for a compound, like formaldehyde. Then, in the properties pane on the left, click the link to "Detailed". HOMO and LUMO energies will show up in the list. $\endgroup$ – Ben Norris Oct 14 '16 at 15:45
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The Pitt Quantum Repository can get you what you want, at least for molecular species.

  1. Go to the PQR at http://pqr.pitt.edu.
  2. Search for a molecule, like benzaldehyde.
  3. Click "Detailed" on the properties pane.
  4. You can see HOMO and LUMO in the list.
  5. Scroll down to the bottom of the page and click on the link to "Get JSON data".
  6. The JSON file will open in your browser or you will download. You should be able to open it with a text editor. There will be a list of orbital energies for the set of molecular orbitals computed from the valence atomic orbitals. For example, for benzaldhyde.

    "homo": -10.168, 
    "lumo": -0.712, 
    "orbitals": [
    "-31.27648", 
    "-30.67710", 
    "-26.81219", 
    "-26.23865", 
    "-23.01445", 
    "-21.46816", 
    "-20.14594", 
    "-18.05465", 
    "-16.39792", 
    "-15.70143", 
    "-14.95762", 
    "-14.67105", 
    "-14.63486", 
    "-14.38581", 
    "-13.35746", 
    "-12.66484", 
    "-12.26937", 
    "-10.28746", 
    "-10.23037", 
    "-10.16786", 
    "-0.71215", 
    "-0.10196", 
    "1.01720", 
    "2.30473", 
    "3.35595", 
    "3.89337", 
    "4.34241", 
    "4.54954", 
    "4.71066", 
    "4.82113", 
    "4.99402", 
    "5.26380", 
    "5.29598", 
    "5.54486", 
    "5.70599", 
    "5.83103", 
    "5.89240", 
    "6.03437"
    ], 
    
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  • $\begingroup$ Though it seems that the database doesn't have all the molecules. For example I cannot find simple molecules as LiH or BeH. $\endgroup$ – MarkAdams Oct 16 '16 at 2:26
  • $\begingroup$ They are there. You need to search by their compound name: Lithium hydride, beryllium hydride $\endgroup$ – Ben Norris Oct 16 '16 at 11:27

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