The ABINIT Users Mailing List ( CLOSED )

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

Dear Liu,

I suggest you look at Test_v4, tests t61-64 (and the README) in
Abinit_4.2.3 and Test_v4, tests 67-70 in Abinit_4.3.x.  In a complex
structure such as this, the clamped-ion elastic tensor calculated
in 4.2.3 does not represent the physical elastic tensor because ion
relaxation can make a substantial contribution.  The relaxed-ion
elastic tensor can be calculated using new capabilities of anaddb
in release 4.3.x.  For now, you probably shouldn't use 4.3.1 for
production results since it is a developers-only release, but 4.3.2
should be along soon and be reasonably robust.

Since the relaxed elastic tensor requires the calculation of the
internal strain parameters (automatic when you do a strain-perturbation
response calculation) and the symmetries of these in such a complex
structure are probably very limited, I suggest you do the strain
calculation using rfstrs = 3 and rfdir = 1 1 1 (in other words,
all six strain components).  You will also have to calculate the
interatomic force constants with rfphon = 1 and rfatpol = 1, (natom)
as in t67.in since these are needed by anaddb.

Be sure to do a well-converged relaxation of the atomic coordinates
and lattice parameters using ground-state calculations before doing
the response function calculations.

Good luck,

Don Hamann

Fabien Bruneval wrote:

I am pretty sure that the actual destination of the following mail was not my inbox but abinit forum...

Fabien

---

Subject:

elastic tensor

From:

liu.yudong@nims.go.jp

Date:

Mon, 1 Mar 2004 18:25:32 +0100

To:

fabien.bruneval@polytechnique.fr

Dear all:
I wish to calculate the elastic tensor of corrundum, alpha-Al2O3 167# space group. but I am not very sure to introduce enough strain perturbations( and in the proper directions ) to get all the components of constant tensor in a input file. Can anyone show me how to input these perturbation?

thank you
ps:
sorry, I can't post my message directly,


  

-- 
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