Hello All,
I am calculating ionization potentials of a system that in its ground
state has two unpaired electrons in a doubly degenerate set of orbitals
that comprise the HOMO. If I wish to calculate the second IP, it is
possible to have doublet and quartet states because there will be three
unpaired electrons (two in the HOMO and one in the next highest
orbital). It seemed to me that I should perform an unrestricted ADF
calculation and specify the numbers of alpha and beta electrons, but
these calculations did not get anywhere near convergence. However, ADF
will let me run a restricted calculation with unpaired electrons. My
question, therefore, concerns the meaning of a restricted calculation
with three unpaired electrons. Have I calculated the quartet state, the
doublet state, an average of the two, or is this result meaningless?
Also, I'd like to know if anyone has had any success performing
unrestricted calculations with two or three unpaired electrons in
orbitals that do not have the same energy.

Thanks very much for your help and I will summarize any responses to the
list.

Best wishes,
Matt
Received on 1998-10-28 19:41:40