N atom

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apple · #1 Post by **apple** » Tue Jul 03, 2012 7:05 pm

hi,
I am running a total energy calculation for N atom. While my calculations correctly predict 3 unpaired electrons for N, I do not understand why the electrons in band #1 for spin1 and spin2 components are at different energies (see band#1 for spin1 and spin2 below). Shouldn't those two energies be the same?
Thank you.

----------------------------------------------
spin component 1

k-point 1 : 0.0000 0.0000 0.0000
band No. band energies occupation
1 -19.8477 1.00000
2 -8.3133 1.00000
3 -8.3133 1.00000
4 -8.3132 1.00000
5 -0.2926 0.00000
6 0.0893 0.00000
7 0.3516 0.00000
8 0.3638 0.00000

spin component 2

k-point 1 : 0.0000 0.0000 0.0000
band No. band energies occupation
1 -15.4169 1.00000
2 -4.2513 0.00000
3 -4.2512 0.00000
4 -4.2512 0.00000
5 -0.0253 0.00000
6 0.3310 0.00000
7 0.3514 0.00000
8 0.3653 0.00000

-----------------------------------------------

alex · #2 Post by **alex** » Wed Jul 04, 2012 10:41 am

Even core-levels are effected by chemistry. See, e.g. XP-Spectroscopy. This is a 2s state. Und VASP does not do restricted open shell methods.

Try an all electron calculation on, e.g. Cs-atom for illustration.

Cheers,

alex

apple · #3 Post by **apple** » Thu Jul 05, 2012 5:02 am

hi Alex,
could you please elaborate a bit more on your answer or point me in a more specific direction? Yes, this is a 2s state, a core-level of a single N atoms. So how is it affected by chemistry?
Thanks.

alex · #4 Post by **alex** » Thu Jul 05, 2012 12:01 pm

Hi apple, I'll try harder this time.

2s of N is a valence state
(1s^2 2s^2 2p^3 orbitals are occupied)

If you've got hard matter (actually matter which can stand high vacuum for some time), you might examine this with photoelectron spectrosopy. If you use X-rays as photons, you end up with XPS.
Here you observe shifts of core-level electrons as a function of the chemical environment.

Cheers,

alex

apple · #5 Post by **apple** » Thu Jul 05, 2012 6:02 pm

Thanks Alex. That was better :-)