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<p>Dear all,</p>
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<p>I am trying to obtain the bands of a 42 atom supercell using Wannier functions. The cell vectors do not actually pertain to a well known symmetry. they are of the form:</p>
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<div>Begin Unit_Cell_cart<br>
bohr<br>
42.82955445336 0.00008690366 0.000000<br>
0.0000188921 9.28402379356 0.000000<br>
0.00000000 0.000000000 28.32670894424<br>
End Unit_Cell_cart<br>
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<p>When I computed the bands in QE, I used the path created by XCrySDen. However this is causing problems in W90 code giving errors such as: (I tried several grids produced by XCrySDen)<br>
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<p><span> kmesh_shell_automatic: Singular Value Decomposition has found a very small singular value</span></p>
<p> and</p>
<p>Non symmetric k points! </p>
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<p>On the other hand trying a 625 point grid produced by the kmesh utility solves the problem but the bands are kind of wiggly and do not correctly produce the bands. My question is : Is this due to the use of grid produced by kmesh which is regular and the
fact that my cell vectors do not belong to a given symmetry? Can this be solved by increasing number of points. In other words can W90 code predict the bands for such a supercell and what could be a possible reason for the wiggling behavior?</p>
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<p>N.B : I have ibrav=0 and the option 'random' was used in projections</p>
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<p>Regards</p>
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<p>Elio</p>
<p>University of Rondonia</p>
<p>Brazil<br>
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