<DIV><FONT size=3>Dear wien2k master:</FONT></DIV>
<DIV><FONT size=3> About questions last time, I adopted the suggestions of Kurt Lejaeghere, here are the new problems:</FONT></DIV>
<DIV><FONT size=3> (1)I changed the 8 atoms to C 1 , C 2,..........C 8, after the sgroup, it found:</FONT></DIV>
<DIV><FONT size=3>=======================</FONT></DIV>
<DIV><FONT size=3>Bravais lattice: Triclinic</FONT></DIV>
<DIV><FONT size=3> a b c<BR> 6.70248100 6.70248100 6.70248100<BR> alpha beta gamma<BR> 90.00000000 90.00000000 90.00000000<BR>=========================</FONT></DIV>
<DIV><FONT size=3> and also there was nothing wrong with symetry, I used all the default setting parameters. Then to kgen:</FONT></DIV>
<DIV><FONT size=3>===========================</FONT></DIV>
<DIV><FONT size=3>inputfiles prepared (07:16:03) <BR>> inputfiles for lapw1c/2c prepared, no inversion present (07:16:03) <BR>> kgen (07:16:03) 1 symmetry operations without inversion<BR> inversion added (non-spinpolarized non-so calculation)<BR> NUMBER OF K-POINTS IN WHOLE CELL: (0 allows to specify 3 divisions of G)<BR><STRONG><FONT color=#ff00cc>10000</FONT></STRONG><BR> length of reciprocal lattic vectors: 0.937 0.937 0.937 21.544 21.544 21.544<BR> Shift of k-mesh allowed. Do you want to shift: (0=no, 1=shift)<BR><STRONG><FONT color=#ff00cc>0</FONT></STRONG></FONT></DIV>
<DIV><STRONG><FONT color=#0000ff size=3>then I get 4631 kpoints in IBZ, too much compared to cubic symetry which only have 300 kpoints.</FONT></STRONG></DIV>
<DIV><STRONG><FONT color=#0000ff size=3><FONT color=#000000>then dstart -c I get 4698 FOURIER COEFFICIENTS CALCULATED UP TO GMIN, also too much compared to cubic symetry which only have 80 FOURIER COEFFICIENTS CALCULATED UP TO GMIN.</FONT></FONT></STRONG></DIV>
<P><FONT color=#0000ff><FONT color=#000000><FONT size=3><STRONG>Here, my question are:<FONT color=#ff0000> Is there something wrong with the parameter ? I know symetry is very low, but are 4631 kpoints in IBZ and 4698 FOURIER COEFFICIENTS reasonable ? (I think this is too huge to calculate)</FONT></STRONG></FONT></P>
<DIV><FONT size=3><STRONG> </STRONG></FONT></DIV>
<DIV><FONT size=3></FONT> </DIV>
<DIV><FONT size=3><STRONG> (2)About the elastic constant, I konw when deform the structure will change the spacegroup, but it should depend on the size you deform. Here I just deformed 0.01 Ang in x axes, I don't think it will need a new spacegroup.</STRONG></FONT></DIV>
<DIV><FONT size=3><STRONG>I also find </STRONG>S. Jalali. already answered this problem long time ago:</FONT></DIV>
<DIV><STRONG><FONT size=3>=================================</FONT></STRONG></DIV>
<DIV><FONT size=3>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, </FONT><A href="http://www.wien2k.at/reg_user/textbooks/elast-UG.ps,"><FONT size=3>http://www.wien2k.at/reg_user/textbooks/elast-UG.ps,</FONT></A><FONT size=3> 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> 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.</FONT></DIV>
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<DIV><FONT size=3><FONT color=#ff0000><STRONG> Here, my questions are: the hyperlink is forbidden although I signed in with our account and</STRONG> <STRONG>password, I don't why ? </STRONG></FONT></FONT></DIV>
<DIV><FONT size=3><STRONG><FONT color=#ff0000> <FONT color=#ff00cc>For cubic system,</FONT></FONT><FONT color=#ff00cc> how to deform it by only 0.01 Angstron in x axes without changing the spacegroup?</FONT></STRONG></FONT></DIV>
<DIV><STRONG><FONT color=#ff00cc size=3></FONT></STRONG> </DIV>
<DIV><STRONG><FONT color=#ff00cc size=3> Any help will be appreicated:)</FONT></STRONG></DIV>
<DIV><STRONG><FONT color=#ff00cc size=3></FONT></STRONG> </DIV>
<DIV><STRONG><FONT color=#ff00cc size=3>Hui</FONT></STRONG></DIV></FONT></FONT> <br><!-- urlfiles --><br><br><!-- footer --><br>