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Thomas
thomaspijper@hotmail.com

I'm not sure if I understand your question correctly. However, I would like to propose that you should calculate the HOMO-LUMO gap with:

Gap = LUMO - HOMO = 2.2 eV

which gives a positive number that looks normal to me.


Kind regards,
Thom



On Sat Apr 20 '13 9:34pm, Siddheshwar Chopra wrote
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>Dear Sir,
>As learnt from the same forum about calculating HOMO-LUMO, I have got the final result as follows:

>Orbital No.     (in eV)
>161     LUMO     -2.25     A
>160     HOMO     -4.45     A

>Hence the GAP= HOMO-LUMO = -2.2 eV

>Now the doubt is that when I plotted the Density of states spectrum, I get to see a gap between the occupied and virtual orbitals (I have attached an image of it for your reference).. Please help me understanding this concept... Just now the calculations have shown a negative value, which in my opinion means overlapping occupied and virtual orbitals. Then how can a gap be seen? Am I going wrong in the calculations or something else. Please help..

>Regards,