[Wien] O2 molecule continue (rmt issue)

[Peter Blaha]

You must modify your O2 struct file.

Make the 2 oxygens "equivalent", i.e. you should have only ONE 
non-equivalent atomic site (NAT=1), but MULT=2 for the 2 oxygens.

This will produce inversion symmetry and all calculations will take less 
time and memory !!!

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

And yes: at the end you must check E-to for your compound (eg. BaO) at 
the E-minimum (after Volume optimization) with an extra calculation 
where you put the small O-spheres.

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

And you must use "equivalent RKmax" values for different compounds 
(always corresponding to the smallest spheres: Eg. BaO with RMT 2.2 and 
O 1.1 for Ba and O, respectively, use RKmax=6. When you do the metallic 
Ba, use identical RMT, but RKmax= 6/1.1*2.2=12 !!!!

I'm preparing a faq page on this topic, which should come up on 
www.wien2k.at in a few hours.


On 11/12/2017 09:11 PM, chin Sabsu wrote:
> Dear Prof. Alay/Peter/Marks/Stefaan or any expert user
>
> As you know molecule calculations take much time (I received your reply
> to my previous query) and as suggested by you all these molecules need
> some good HPC facility that I do not have.
>
> Therefore, to avoid the multiple heavy repetitive calculations or O2
> molecule, I need some hints on rmt issue from atomic to crystalline
> structures.
>
>
> As Prof. Marks and Alay said in my previous post [1, 2] that what
> whatever rmt I take for O2 molecule it should be same for all oxides
> means for all Oxygens in the system of BaZrO3 (BaO, ZrO2, O, etc) and
> this also should apply to Ba (Ba atom and crystal, BaO, BaZrO3) and Zr
> (Zr atom and Zr crystal, ZrO2).
>
> Means the rmt must be same for all same elements for all components of
> the calculations.    Is it?
>
> If the above statement remains true then I could not manage the same rmt
> for Oxygen in all structures: O, O2, BaO, and BaZrO3; Barium in Ba, Ba2,
> BaO, and BaZrO3; and same hold for Zr.  For example, for O2 I have 1.16
> rmt then for O/BaO/ BaZrO3 it is 2.5/2.51.90  which is quite different
> from O2 [I am sending all structure in in your email as I am not able to
> send here].
>
> How should I fix this?  Is it okay if I use rmt set manually?
>
> I am so confused and on limited resources, I am not able to start the
> calculation. Your help will be much helpful and will be appreciated.
>
>
> [1] Re: [Wien] :WARN : WARNING: RKmax reduced due to NMATMAX
> <https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg16734.html>
>
> [2]
> https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg16736.html
>
>
> Thank you in advance,
>
> Chin Sabsu
>
>
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-- 

                                       P.Blaha
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-165300             FAX: +43-1-58801-165982
Email: blaha at theochem.tuwien.ac.at    WIEN2k: http://www.wien2k.at
WWW:   http://www.imc.tuwien.ac.at/TC_Blaha
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