## Firefly and PC GAMESS-related discussion club

Learn how to ask questions correctly

** HOMO-LUMO GAP CALCULATION DOUBT.... **
Siddheshwar Chopra

sidhusai@gmail.com

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,

Sat Apr 20 '13 9:34pm

This message read **1050** times