[Pw_forum] Lattice Parameters in Supercell

[Yao Yao]

Hi Angga,

Generally, yes if you do not use CELL_PARAMETERS card, which means the vectors 
are standard vectors generated from ibrav value you set.

However if you do use CELL_PARAMETERS card and set ibrav=0, ony A is used. In 
this case, A is simply a scaling factor. You can multiply A by 2, or multiply 
the vectors by 2. You also need to take care for atoms positions. For 
"crystal", atom position is scaled by both a/celldm(1) and cell vector while 
for "alat", it's scaled only by a/celldm(1).

Regards,
Yao

On Sat, 8 Dec 2012 12:02:25 AM Angga Fauzi wrote:

Dear all,


I am trying a scf calculation in my system. My system is 2x2x2 ZnO supercell 
with 32 atoms. The lattice parameters of unit cell of ZnO are a=b=3.2495 
angstrom and c=5.2069 angstrom. My question is should I multiply the lattice 
parameters by 2 when I perform a scf calculation for my system?


Regards,
Angga



-- 
Yao Yao
PhD. Candidate
3rd Generation Strand
ARC Photovoltaics Centre of Excellence
University of New South Wales
Sydney, NSW Australia
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