[Wien] Structure problem in NiAs-type

[Fecher, Gerhard]

Typical handbook-not-read-error

The answer  already was given very often in this forum
the positions from your cif file are not precise enough
1/3 is not 0.3333 you need to give more digits 

For high symmetry positions you have the same for other fractions 2/3, 1/7, 5/9 or whatever else

Take also care on the setup that Wien2k uses for hexagonal structures

Ciao
Gerhard

DEEP THOUGHT in D. Adams; Hitchhikers Guide to the Galaxy:
"I think the problem, to be quite honest with you,
is that you have never actually known what the question is."

====================================
Dr. Gerhard H. Fecher
Institut of Inorganic and Analytical Chemistry
Johannes Gutenberg - University
55099 Mainz
________________________________________
Von: wien-bounces at zeus.theochem.tuwien.ac.at [wien-bounces at zeus.theochem.tuwien.ac.at]" im Auftrag von "王静 [wangjingjing at ciac.jl.cn]
Gesendet: Sonntag, 1. Juli 2012 06:06
An: wien
Betreff: [Wien] Structure problem in NiAs-type

Hi, there!
   When I tried to calculate some properties about NiAs, there are some problems.
(1)     I uploaded a NiAs.cif with symmetry (space group P63/mmc, No.194). Everything goes well. Nevertheless, when I uploaded the structure without symmetry, say, space group P1, No. 1, the symmetry found by WIEN is in space group Cmcm, No.63. This is weird.
(2)     Using the P1 symmetry, I tried to substitute half of the Ni by other atoms, the symmetry found by WIEN is C2/m, No. 12. Then I restart the StructGen. When “x sgroup -up” is executed, the following message is met,

Error lat==HEXAGONAL in det_pgrp()
Accuracy problem. Please run with different tolerance (x sgroup -settol .00000100)
Error lat==HEXAGONAL in det_pgrp()
0.000u 0.000s 0:00.00 0.0%      0+0k 0+0io 0pf+0w
error: command   /software/wien2k/sgroup -wi NiAs.struct -wo NiAs.struct_sgroup  -set-TOL=0.00001   failed

One the other hand, by using MS, I found the half substituted case is in space group P-3M1, No 164. I think it might be necessary to transfer the internal atomic position to be rhombohedral form. Therefore, I transferred the internal positions.
                      Hexagonal position        rhombohedral position
Ni                        (0 0 0)                        (0 0 0)
Atoms substituted Ni     (0 0 0.5)                    (0.5 0.5 0.5)
As                      (1/3 2/3 0/25)          (0.58334 0.58333 0.58333)

The two positions (0.5 0.5 0.5) and (0.58333 0.58333 0.58333) turn out to be close to each other, giving RMT as small as 0.5 for As.

Could someone help me out? Thanks very much!


                     Wang Jing
　　　　　　　　wangjingjing at ciac.jl.cn
　　　　　　　　　　2012-07-01
_______________________________________________
Wien mailing list
Wien at zeus.theochem.tuwien.ac.at
http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien