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["Anglade Pierre-Matthieu" <anglade@gmail.com>]

Hi,

I would quite gladly help you and would already have done so if I was
able to ! You know, I've read your multiple message on the forum
list... Yet I was not having any clue about the kind of crystal you
wanted to consider (as most other readers of the forum probably).

However the joined article shed a new light on your problem. Let's
first start with a very simple questions: the articles
states that the I cell parameters for M phase should be:
acell 5.292 10.902 5.11 angst
angdeg 90 96.44 90
are you sure that your conversion from the double cell to the unit
cell is correct ?

If I had to make the calculation I would write the following: the I
cell is described by the vector:
a (1 0 0)
b (0 1 0)
c (e 0 1)
You want the unit cell which is made of
a'=-0.5a+0.5b+0.5c ...
So the final rprim should be:
0.5(e-1) 0.5 0.5
(1+e)0.5 -0.5 0.5
(1-e)0.5 0.5 -0.5
supposing I do not make any mistake and using your values for rprim.

Could you try this input replacing your angdeg by my rprim ?

regards

PMA


2008/3/25 xiangsitian <xiangsitian@163.com>:
>
>
>  Dear Anglade;
>     This problem puzzled me for a long time.I find the abinit cannot
> recongnize the space group of M-type YTaO4.The space group of M-type YTaO4
> is I2(spgroup 5) and the atoms coordinate originate from Acta
> Cryst.(1967).23,939(written by G.M.Wolten).This article is attached in
> accessory. I used primitive cell.My input file is following as:
> #Definition of the unit cell
> acell 9.9003 20.5848 9.5545
> angdeg 69.3474 69.3474 115.132
> #Definition of the k-point grids
> occopt 1
> kptopt 1
> nshiftk 1
> shiftk 0.5 0.5 0.5
> #Definition of the atom types
> ntypat 3
> znucl 39 73 8
> #Definition of the atoms
> natom 12
> typat 2*1 2*2 8*3
> xred
> -0.476000 0.476000 0.000000 #Y
> 0.262000 0.738000 -0.500000
> 0.000000 0.000000 0.000000 #Ta
> -0.214000 0.214000 0.500000
> 0.107500 0.407500 0.058900 #O
> -0.081800 0.718200 -0.064000
> 0.745100 0.761100 -0.560800
> 0.482800 1.142800 -0.559000
> -0.407500 -0.107500 -0.058900
> -0.718200 0.081800 0.064000
> -0.761100 -0.745100 0.560800
> -1.142800 -0.482800 0.559000
> #Definition of the planewave basis set
> ecut 40 # Maximal kinetic energy cut-off, in Hartree
> ngkpt 3 3 3
> #Definition of the SCF procedure
> nstep 50
> toldfe 1.0d-9
> diemac 2.0
> But abinit cannot recognize I2 space group. What's wrong?Can you help me to
> try it?Thank you in advance.I hope your reply。
>
>
> dongxiang
>
>
>
>
> ________________________________
>  中 国 最 强 网 游 --- 网 易 梦 幻 西 游 ，166 万 玩 家 同 时 在 线



-- 
Pierre-Matthieu Anglade