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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