The ABINIT Users Mailing List ( CLOSED )

[Masayoshi Mikami <mmikami@yk.rim.or.jp>]

Dear /Per Andersson,

Although I am not such an expert in the Rare-earth field, 
but I wish the following post might be interesting:
 http://www.abinit.org/wws/arc/forum/2003-08/msg00019.html
In any PPs (HGH, TM, Vanderbilt, ...), many tests may 
be awaited ... good luck !

As for the bandcalculation methods (without relying on PPs):
Force calculation (on ions) is available in (F)LAPW/(F)LMTO codes:
e.g. WIEN2k, ... 
But I think that most of them cannot treat stress calculation
(for cell shape relaxation) at present. 
Still, I had came across the following paper:
  T. Thonhauser, C. Ambrosch-Draxl and D. J. Singh
  Solid State Communications 124, 275 (2002)
But I do not know whether this kind of method is now
available in the latest (F)LAPW pakcages or not. 
Let us wait and see ...

Hope this helps,
Masayoshi 

> From: perand@foi.se
> Subject: [abinit-forum] pseudopotentials and pressure
> Date: Tue, 23 Sep 2003 09:57:05 +0200
> 
> Dear Forum
>
> I am trying to calculate the (p,V,T) phase diagram of
> a few compounds containing rare earths. As these
> materials have several degrees of freedom, both internal
> and cell shape, which can change a lot under compression,
> I have been trying to use ABINIT for the relaxations.
> To describe the different atoms I have chosen HGH pseudo
> potentials with spin-orbit interaction included.
> 
> My problem is that for large compressions I notice a
> substantial difference compared to the results from a
> very stable and accurate FP-LMTO code (for a fixed
> structure, no relaxation in this FP-LMTO). I assume
> that this is due to the validity of the PPs and the
> choice of rloc (the fitting radius). The PPs I have
> made are already extremly hard (ecut > 120 Ha) and
> they are pushing the limits with regards to the
> recommendations on how to create HGH PPs in the README
> in that code.
> 
> Are there any references on PPs and pressure or do
> anyone in the forum have any experience with this
> problem?
> 
> Is there some code which can do ionic and cell shape
> relaxations without using PPs aviable?
> 
>  TIA!
> 
> /Per Andersson