The ABINIT Users Mailing List ( CLOSED )

[Bernard Amadon <bernard.amadon@cea.fr>]

Dear Qian Guangrui,

Concerning the first two points,

(1) If you do not use spin orbit coupling, nspinor=1, in the other case 
nspinor=2.
In the case where you want to use spin orbit coupling, you then use 
non-collinear magnetism,
and thus you have to precise the direction of the imposed magnetisation 
with the variable spinat
(see 
http://www.abinit.org/Infos_v5.6/input_variables/vargs.html#spinat). For 
NiO, and to my knowledge
nspinor=1 is fine.
If you do not use spin orbit AND you impose the density matrix, spinat 
is not very useful, because the magnetisation
will be imposed by the starting density matrix.

(2) In some cases, it can appear that a given density matrix does not 
lead to convergency.
You can then choose another starting density matrix. Note the precise 
order of d-orbitals  (see
http://www.abinit.org/Infos_v5.6/input_variables/varpaw.html#dmatpawu). 
For example note that
the five columns for the input density matrix are xy,yz,z2,xz,x2-y2 (so 
t2g t2g eg t2g eg).
The filling of orbitals depends on the geometry, so I cannot easily 
check your input density matrices without the
full input.

Best
Bernard Amadon



hyello25@gmail.com a écrit :
> Hi, everyone
>
> I am now doing some calculations of PAW+U, I met some problems.
> (1) I am not so sure about the variable 'spinor', examples V5#8 & V5#16 give
> different 'spinor' for NiO. I am  confused which one is more reasonable? Is 
> the
> value of this variable  not very important? While we should care more about
> whether it is positive or negative?
>       For example, supposed in ferromagnetic spin-polarized system NiMnO3 , (
> Ni(+2), Mn(+4), O(-2)), we can give the the specific dmatpawu, with nsppol=2,
> nspinor=1, nspden=2, what dose the 'spinat' should be set?
> dmatpawu            # The initial density matrix
>      # Mn atom 1 (spin-up )
>      0.00000    0.00000    0.00000    0.00000    0.00000
>      0.00000    0.00000    0.00000    0.00000    0.00000
>      0.00000    0.00000    0.00000    0.00000    0.00000
>      0.00000    0.00000    0.00000    0.00000    0.00000
>      0.00000    0.00000    0.00000    0.00000    0.00000
>      # Mn atom 1 (spin-down )
>      1.00000    0.00000    0.00000    0.00000    0.00000
>      0.00000    1.00000    0.00000    0.00000    0.00000
>      0.00000    0.00000    0.00000    0.00000    0.00000
>      0.00000    0.00000    0.00000    0.00000    0.00000
>      0.00000    0.00000    0.00000    0.00000    1.00000
> #-----------------------------------------------------------------------#
>      # Mn atom 2 (spin-up )
>      0.00000    0.00000    0.00000    0.00000    0.00000
>      0.00000    0.00000    0.00000    0.00000    0.00000
>      0.00000    0.00000    0.00000    0.00000    0.00000
>      0.00000    0.00000    0.00000    0.00000    0.00000
>      0.00000    0.00000    0.00000    0.00000    0.00000
>      # Mn atom 2 (spin-down )
>      1.00000    0.00000    0.00000    0.00000    0.00000
>      0.00000    1.00000    0.00000    0.00000    0.00000
>      0.00000    0.00000    0.00000    0.00000    0.00000
>      0.00000    0.00000    0.00000    0.00000    0.00000
>      0.00000    0.00000    0.00000    0.00000    1.00000
> #-----------------------------------------------------------------------#
>      # Ni atom 1 (spin-up )
>      1.00000    0.00000    0.00000    0.00000    0.00000
>      0.00000    1.00000    0.00000    0.00000    0.00000
>      0.00000    0.00000    1.00000    0.00000    0.00000
>      0.00000    0.00000    0.00000    1.00000    0.00000
>      0.00000    0.00000    0.00000    0.00000    1.00000
>      # Ni atom 1 (spin-down )
>      1.00000    0.00000    0.00000    0.00000    0.00000
>      0.00000    0.00000    0.00000    0.00000    0.00000
>      0.00000    0.00000    1.00000    0.00000    0.00000
>      0.00000    0.00000    0.00000    0.00000    0.00000
>      0.00000    0.00000    0.00000    0.00000    1.00000
> #-----------------------------------------------------------------------#
>      # Ni atom 2 (spin-up )
>      1.00000    0.00000    0.00000    0.00000    0.00000
>      0.00000    1.00000    0.00000    0.00000    0.00000
>      0.00000    0.00000    1.00000    0.00000    0.00000
>      0.00000    0.00000    0.00000    1.00000    0.00000
>      0.00000    0.00000    0.00000    0.00000    1.00000
>      # Ni atom 2 (spin-down )
>      1.00000    0.00000    0.00000    0.00000    0.00000
>      0.00000    0.00000    0.00000    0.00000    0.00000
>      0.00000    0.00000    1.00000    0.00000    0.00000
>      0.00000    0.00000    0.00000    0.00000    0.00000
>      0.00000    0.00000    0.00000    0.00000    1.00000
> #-----------------------------------------------------------------------#
>
> (2) When I do some calculating some complicated systems with PAW+U, it is very
> hard to get convergence in a scf process, sometimes 200 scf steps still dose
> not work. How can I improve this? 
>
> (3) Is LSDA+phonon possible in ABINIT? If dose, is there any specific
> conditions for the pseudopotentials ?
>
> Thanks a lot in advance.
>
> Bests,
> Qian
>
> -------------------------------------
> Qian Guangrui
> Graduated students
> Physics Department
> Nanjing University
> Nanjing 210093 China
> E-mail: hyello25@gmail.com
>
>