[Wien] Poisson ratio

[Peter Blaha]

> I want to calculate a tetragonal cell, which is deviated from a cubic
> structure (elongation of one lattice parameter). Is it possible to change
> or add a Poisson ratio to simulate a distortion (stress-strain) more
> exact?

You have to setup a structure with a slight distortion (make it slightly
non-cubic). Then initialize (the symmetry must be lower than cubic!!).

After init_lapw you can change a,c back to the original (cubic) values.

Then run optimize vol, c/a. Select c/a (at constant volume).

You must fit the results yourself (e.g. by ORIGIN or EXCEL,...) and
calculate Poissons ratio from that.

If your structure is cubic, there is also a module "ELAST" which gives
you all elastic constants (adapted only for cubic structures).

Regards

                                      P.Blaha
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-15671             FAX: +43-1-58801-15698
Email: blaha at theochem.tuwien.ac.at    WWW: http://info.tuwien.ac.at/theochem/
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