[Wien] Bi almost cubic

[delamora]

Comments below

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Some 5 years ago I was interested in the total energy of Bi and checked what happens with Bi if setting z=1/4
using PBE the semimetallic character (or nearly semimetallic with SO) was conserved.
The band structure between z=0.23457217 and 1/4 was not much different

Is your total energy changing continously ?
--------
Z       Ene
0.249;   -86326.25852144
0.2499; -86326.25475092
0.25; -43163.12738079*2=-86326.25476158
Was, for z=0.25, the cell reduced to a semi-cubic with only one atom in the cell?
--------
Ciao
Gerhard
------------
Saludos
Pablo
________________________________________
Von: Wien [wien-bounces at zeus.theochem.tuwien.ac.at] im Auftrag von delamora [delamora at unam.mx]
Gesendet: Mittwoch, 6. Juli 2022 23:44
An: A Mailing list for WIEN2k users
Betreff: [Wien] RV: Bi almost cubic

Dear WIEN2k community,
Its me again reporting something that does not seem correct;
Bi is almost cubic, next to Po, the only element with a true simple cubic unit cell
------------
Bi unit cell parameters;

R   LATTICE,NONEQUIV.ATOMS:  1
MODE OF CALC=RELA unit=ang
  8.591340  8.591340 22.415740 90.000000 90.000000120.000000
ATOM  -1: X=0.23592070 Y=0.23592070 Z=0.23592070
ATOM  -1:X= 0.76407930 Y=0.76407930 Z=0.76407930
Bi1        NPT=  781  R0=0.00000500 RMT=    2.5000   Z: 83.000
______
If XYZ => 0.25
the cell reduces to half and is almost a cube with a little distortion in the 111 direction with an angle of 90 => 87.54
What atracted me was that the compound almost has a gap at Ef, with the above structure XYZ=0.2359
but if this atomic position is moved towards
XYZ=0.2359 => 0.25
the "gap" diminishes, but it does not disappear even at
XYZ=0.2499
but if XYZ=0.25
then, as mentioned above, the cell is reduced and the "gap" disapears
As can be seen, with
XYZ=0.249 and 0.2499 the "gap" is almost the same, but adding 0.0001 it disappears
My question is, why it disappears when the cells with XYZ=0.2499 and 0.25 are almost the same but with XYZ=0.25 the cel reduces, but still it should give the same DOS.

Cheers

Pablo
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