[Wien] elastic constant

[Saeid Jalali]

    The elastic constants can be derived from  second derivatives of the total energy with respect to appropriate  deformations. The appropriate deformations are generalized coordinates which  can be lattice parameters or angles of the proper unit cells.
  For cubic structure, where the matrix representation of elastic tensors has  only 3 independent components, i.e.  C11, C12, C44=C66, you can use the  elast package of wien2k, http://www.wien2k.at/reg_user/textbooks/elast-UG.ps,  to calculate these constants.
  For other structure one must first find the proper deformations and plot E  versus them and then try to evaluate the second derivatives of the curves. 
  
  Regarding your second question, I can say that, density of states influences  not only the elastic constants, but also any other physical quantities. This is  the density of state that differs from one case to the others, and this is why  one case has different properties from the others. Density of states in the energy-space  plays an important role in materials, which can be compared to the role of  charge densities in the real (coordinate)-space.
  
  Your,
  S. Jalali.
    
Belkadi Amina <amina_belkadi2003 at yahoo.fr> wrote:  

Dear users:
 
   I use wien2K and I need to calculate the elastic
constant but the problem is how to do it and what is
the comand used???
    
  
I have a wurtzite structure 
Furthermore, from the subroutine "setelast.f" it seems
as though Wien2k sees a relationship between the
elastic constants and density of states. Is this
correct? 
  Thank you. 
B.Amina






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Sincerely yours,
S. Jalali.
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Saeid Jalali Asadabadi,
Department of Physics, Faculty of Science,
University of Isfahan (UI), Hezar Gerib Avenue,
81744 Isfahan, Iran.
Phones:
Dep. of Phys.      :+98-0311-793 2435
Office             :+98-0311-793 2430
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E-mail             :s_jalali_a at yahoo.com
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