I tried optimizing a ligand using B3LYP and 6-31G basis set. I am not very sure how can I find the energy for the HOMO and LUMO orbitals. I am interested in calculating the Energy Gap (delta E) = LUMO - HOMO (eV). Can someone please suggest me where to exactly find the energy of HOMO and LUMO in the output file?
After optimization in ORCA you will find the following section in out file
----------------
ORBITAL ENERGIES
----------------
NO OCC E(Eh) E(eV)
0 2.0000 -19.169164 -521.6195
1 2.0000 -19.169152 -521.6191
2 2.0000 -14.314665 -389.5218
3 2.0000 -14.314619 -389.5206
4 2.0000 -10.285793 -279.8906
From this table you can easily get the energies of any otbital.
Hope this helps...
Aside from directly reading output file, an easier way to realize this is using Multiwfn (http://sobereva.com/multiwfn). First, use this command to convert test.gbw file to test.molden.input: orca_2mkl test -molden ,where orca_2mkl is a utility in the ORCA package. Then load the test.molden.input file into Multiwfn, enter main function 0, you can directly find gap and related information on console window:
Note: Orbital 11 is HOMO, energy: -0.470352 a.u. -12.798918 eV
Orbital 12 is LUMO, energy: 0.108714 a.u. 2.958263 eV
LUMO/HOMO gap: 0.579066 a.u. 15.757181 eV 1520.337152 kJ/mol
In addition, in the upper left corner of GUI window of main function 0, you can select "Orbital info."-"show up to LUMO+10" to print all orbital information up to LUMO+1 on console window, e.g.
Orb: 10 Ene(au/eV): -0.470353 -12.7990 Occ: 2.000000 Type: A+B (a)
Orb: 11 Ene(au/eV): -0.470352 -12.7989 Occ: 2.000000 Type: A+B (a)
Orb: 12 Ene(au/eV): 0.108714 2.9583 Occ: 0.000000 Type: A+B (a)
And if you want to visualize orbital isosurface, you can select corresponding index in the table at the lower right corner of the GUI window, the orbital will immediately be shown on the screen.
% output
Print[P_Basis]2
Print[P_MOs]1
end
you could use commands above to show the exact value of LUMO and HOMO in output file.
@Debasish Mandal There are two sets of Orbital energies, what each of them represent, please? I found out, the sets are almost the same, when calculate without solvent, and quite different, if calc. with solvent. So I think, the second one is there for case of solvent? But not sure...
for a large number of files, i made this simple bash script which may help. Regards, PLRK
#!/bin/bash
if test -z "$1"
then
echo "Usage: provide "
else
homo=`grep 'ORBITAL ENERGIES' -A40 $1 |grep '1.0000' |tail -1 |awk '{print $4}'`
lumo=`grep 'ORBITAL ENERGIES' -A40 $1 |grep '0.0000' |head -1 |awk '{print $4}'`
grep 'ORBITAL ENERGIES' -A40 $1 |grep '1.0000' |tail -1;
grep 'ORBITAL ENERGIES' -A40 $1 |grep '0.0000' |head -1;
echo "HOMO-LUMO gap of alpha orbitals::"
python -c "print $homo - $lumo"
fi
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