[Wien] open shell case [Si and Ge]

[Stefaan Cottenier]

Following Hund’s rules, the atomic ground state for Si and Ge is spin-polarized (‘open shell’):

https://www.webelements.com/silicon/atoms.html

Hence, yes, you need -sp to find a meaningful value for the free atom total energy.

Stefaan


Van: Wien [mailto:wien-bounces at zeus.theochem.tuwien.ac.at] Namens Gavin Abo
Verzonden: vrijdag 3 november 2017 5:42
Aan: wien at zeus.theochem.tuwien.ac.at
Onderwerp: Re: [Wien] open shell case [Si and Ge]

Feel free to correct me if I'm wrong, but I think Si and Ge have an even number of electrons (or paired electrons).

For Si, 4 electrons in the 3s^2 3p^2.  For Ge, 4 electrons in the 4s^2 4p^2. [1]

This making them closed shell [2].

In Prof. Blaha's example for free atoms [3], spin-polarized (runsp_lapw) is used for open shell (or non-closed shell [4]) Li (1 electron in 2s^1) and B (3 electron in 2s^2 2p^1) and non-spin polarized is used for closed shell Be (2 electron in 2s^2).

I don't know why it is fluctuating, diverging?  Is the box you used containing the free atom large enough?  I remember that 12x12x12 angstrom usually might be large enough [5].

[1] https://en.wikipedia.org/wiki/Electron_configurations_of_the_elements_(data_page)
[2] https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg11320.html
[3] https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg16691.html
[4] http://susi.theochem.tuwien.ac.at/reg_user/faq/cohesive.html
[5] https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg12815.html
On 11/2/2017 7:06 PM, chin Sabsu wrote:
Dear Peter Sir,

Do Si [S^23P^4]  and Ge [4S^24P^2] are also an open shell case?

Because my Si atomization energy is fluctuating without -sp switch after 55 scf cycles also.



Sincerely

Chin
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