<div class="MsoNormal">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.<br> 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.<br> 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. <br> <br> 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.<br> <br> Your,<br> S. Jalali.</div> <br><b><i>Belkadi Amina <amina_belkadi2003@yahoo.fr></i></b> wrote:<blockquote class="replbq" style="border-left: 2px solid rgb(16, 16, 255); margin-left: 5px; padding-left: 5px;"> <style type="text/css"><!-- DIV {margin:0px} --></style><div style="font-family: times new roman,new york,times,serif; font-size: 12pt;"><div style="font-family: times new roman,new york,times,serif; font-size: 12pt;"><div><div><br><br>Dear users:<br> <br> I use wien2K and I need to calculate the elastic<br>constant but the problem is how to do it and what is<br>the comand used???<br> <br> <br>I have a wurtzite structure <br>Furthermore, from the subroutine "setelast.f" it seems<br>as though Wien2k sees a relationship
between the<br>elastic constants and density of states. Is this<br>correct? <br> Thank you. <br>B.Amina<br><br><br></div></div></div></div>_______________________________________________<br>Wien mailing list<br>Wien@zeus.theochem.tuwien.ac.at<br>http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien<br></blockquote><br><BR><BR>Sincerely yours,<br>S. Jalali.<br>/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/<br>Saeid Jalali Asadabadi,<br>Department of Physics, Faculty of Science,<br>University of Isfahan (UI), Hezar Gerib Avenue,<br>81744 Isfahan, Iran.<br>Phones:<br>Dep. of Phys. :+98-0311-793 2435<br>Office :+98-0311-793 2430<br>Fax No. :+98-0311-793 2409<br>E-mail :s_jalali_a@yahoo.com<br>www :http://www.ui.ac.ir<br>/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/<p>
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