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["M.G.A.Tijssens" <M.G.A.Tijssens@LR.TUDelft.NL>]

Dear abiniters,
I have been calculating elastic constants for NiTi. One deformation
mode of the unit cell that I use is a simple shear. To accomplish this
I include in the input file the lines:



rprim: 1.0    0.0    0.0
       0.0    1.0    0.0
       0.0    0.0    1.0

rprim+ 0.0    0.02   0.0
       0.0    0.0    0.0
       0.0    0.0    0.0

As I understood, these give the directions of the vectors spanning
the unit cell and they are multiplied by the dimensions given in
acell (which is three times 5.718 in my case, corresponding to the
minimum energy lattice parameter found for Troullier-Martins
potentials).

The results that I anticipated is that the energy will increase, and
reach a maximum when (the first line of) rprim equals 1.0 0.5 0.0
since at that moment the unit cell has been sheared by 45 degrees.

However, the maximum is reached when the first line reads 1.0 1.0 0.0.
Can anybody tell me if this is a mistake in abinit (doubtfull...)
or my misinterpretation of rprim. If so, how then should I interpret
rprim (and I did read the help file for this variable!).

Thanks for any suggestions,
Martin Tijssens 
-- 
Dr. M.G.A. Tijssens               T: +31 15 278 9552
Delft University of Technology    F: +31 15 261 1465
Dept. of Aerospace Engineering    E: M.G.A.Tijssens@lr.tudelft.nl
Postbus 5058
2600 GB  Delft
The Netherlands