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["Wu Rongqin" <g0203654@nus.edu.sg>]

Dear all,

    When I tried to do calculations on piezoelectric properties on B3 type 
lattice, I found that the piezoelectric tensors are all zero! I tried for 
several different materials in the same B3 structure, and the results are all 
zero! Why this structure do not possess piezoelectricity? Or my calculation 
is wrong?

Rongqin Wu

-----Original Message-----
From: Masayoshi Mikami [mailto:mmikami@yk.rim.or.jp] 
Sent: 2004年3月20日 11:46
To: forum@abinit.org
Subject: Re: [abinit-forum] Pseudos for YVO4

Dear Aldo,

Just one more thing: 
In my previous mail, I assumed that your xred in the input 
were already well optimized before trying "optcell 1". 
If not, please try ionmov 2(or 3) without unitcell optimization.

If "optcell 1" (or optcell 2) do not work to get converged 
results, your initial geometry might be far from the plausible
geometry. In such case, you might want to prepare dataset 
with different volumes, and for each volume you could try 
"optcell 3" with "ionmove 2 or 3". (Still, for each volume,
the initial xred should be optimized with ionmov 
before trying "optcell 3")
The equilibirium volume may then be obtained with fitting
such as Murnaghan's equation of state.

Best wishes,
Masayoshi