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QuantumATK => General Questions and Answers => Topic started by: hadi9827 on February 22, 2021, 12:24

Title: Problem in finding HOMO-LUMO because of partial occupations
Post by: hadi9827 on February 22, 2021, 12:24
Dear all,

How can I determine HOMO-LUMO for this structure? there are some partial occupations in some orbitals! the script and the molecular energy spectrum have been attached.

 562  -1.457714e+00   2.000000e+00
  563  -1.396535e+00   2.000000e+00
  564  -2.405055e-01   1.999818e+00
  565  -7.608169e-02   1.899860e+00
  566   2.848218e-02   4.988281e-01
  567   3.148024e-01   1.029389e-05
  568   3.187673e-01   8.830246e-06
  569   3.190502e-01   8.734142e-06
  570   5.065160e-01   6.193482e-09
  571   5.070444e-01   6.068169e-09

Thanks
Best regards,
Title: Re: Problem in finding HOMO-LUMO because of partial occupations
Post by: hadi9827 on February 22, 2021, 19:45
Anyone to help me please?
I think the problem is the number of electrons. The number of electrons for the solo slab is 1080 and for the solo molecule is 58, but for the whole structure is 1138.4 !!!
Thanks
Title: Re: Problem in finding HOMO-LUMO because of partial occupations
Post by: filipr on February 23, 2021, 12:15
Your structure is a slab, not an isolated molecule, and it has periodic boundary conditions. The energy spectrum will therefore have a dispersion and you need to calculate the k-resolved band structure instead of the molecular energy spectrum (which are just the eigenenergies at the Gamma point, k=(0, 0, 0)).