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["D. R. Hamann" <drh@bell-labs.com>]

Dear Rongqin,

"Rigid-atom" (from abinis) and "clamped ion" (from anaddb) mean the same
thing.  The numbers are different because the abinis output is in atomic
units, and the anaddb in SI units.  The relaxed-ion piezoelectric
constants from anaddb contain all contributions and are the total
piezoelectric tensor.

The latest version of the lr.pdf notes is Infos/Theory/vanderbilt-anaddb-
notes.pdf  These are quite complete, and should provide answers to all
these questions.  The term "proper" in this context is explained there
and in a reference (also cited in Test_v4/README - 66).

Regards,
Don Hamann

Wu Rongqin wrote:

Dear all,

 

When I looked into Test_v4/t65-t70, I encountered some puzzles.

1 In the t67.out there is a Rigid-atom proper piezoelectric tensor, it has non-zero values 0.01422, 0.00647 and 0.0108. in t68.out, there are ‘ Proper piezoelectric tensor (clamped ion)’ and ‘Proper Piezoelectric tensor ( relaxed ion)’. I only know that ‘relaxed ion’ tensor is the contribution of relative motion of negatively and positively charged ion, calculated from Born effective charge. But I can not distinguish ‘clamped ion’ tensor and ‘Rigid-atom’ tensor. Can somebody give some hints? Although lr.pdf has some info, but far from completeness.

2 what is the total piezoelectric tensor, does the relaxed ion include the clamped ion part?

 

Regards

 

Rongqin

-- 
D. R. Hamann				Phone: 908-582-4454
Director, Theoretical Materials    	Fax:   908-582-4702
  Physics Research (retired)		email: drh@physics.bell-labs.com
Bell Laboratories 
Lucent Technologies
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Murray Hill, NJ 07974-0636 USA