Firefly and PC GAMESS-related discussion club

 
Learn how to ask questions correctly  
 
 

 

Siddheshwar Chopra
sidhusai@gmail.com

Regards,


Dear Thomas,
n Sun Apr 21 '13 3:01pm, Thomas wrote
--------------------------------------
>Dear Siddheshwar,

>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
>--------------------------------------------------
>>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,