[gpaw-users] question regarding delta-scf in gpaw

[Thomas Olsen]

Hi Abhishek



>1) I want to understand how can I get the correct "n" for my system? My molecule is very very large and its not easy to just >guess into which orbitals the excitations will take place. Is there a way to determine this automatically? Can I just directly >choose it to be the 'n' which is the band index of the first unoccupied state ?

I am not sure what you mean by "guess". You choose it yourself. If you want the Lumo you choose the first unoccupied state. If you want to excite into the Lumo+1 you choose the second unoccipied state and so on.



>2) Whats the meaning of molecule  = [0,1]. Does this correspond to 'C' and 'O' in the tutorial? Does it mean I must use >molecule = [0,1,2,3,4....120] in my simulations ?

Yes

>3) Also further, on the page it seems that 'bands:-1' is always used in convergence. I wanted to >understand is this has got anything to do with leaving the last band of the occupies bands out of >convergence for lumo? I want to know this to understand, for e.g. I want the excitation energy to the
>level above lumo, then should I use 'bands:-2'
I am not sure, but you should just make sure that you converge the unoccupied states you excite to.

BR
/Thomas
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