[Wien] Fundamental Question of Spin-orbit

[Chiung-Yuan Lin]

Dear all,
  I have the following fundamental questions coming to my mind
when recently doing Wien2k SOC calculations:

Is the SOC contribution in a DFT calculation negative definite?

Or more precisely speaking, is E_{noSO} - E_{SO} always >0 ?

I just realize that the above statement seems to be true for all
SOC calculations I have done so far.
I would like to ask other people's experiences, and hope someone
may be able to formally justify such a statement if it is indeed true.


Thanks,
Chiung-Yuan