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<div><div>I am new to wannier90 and after some experiences with it, I found a problem.</div><div><br></div><div>I am using wannier90-2.1.0. Take example05 diamond as an example.</div><div><br></div><div>The example uses delicate initial projection</div><div><br></div><div><div>f=0.0,0.0,0.0:s</div><div>f=0.0,0.0,0.5:s</div><div>f=0.0,0.5,0.0:s</div><div>f=0.5,0.0,0.0:s</div></div><div><br></div><div>These are s orbitals located on center of C-C bond. I say the projection is delicate, because the spread is almost minimal even in the first iteration, so the convergence is fast. I use below convergence options</div><div><br></div><div><div>conv_window = 10</div><div>conv_tol = 1.d-15</div></div><div><br></div><div>the convergence is done in 74 steps. And examine hr.dat file, all imaginary part is zero.</div><div><br></div><div><div> -3 1 1 1 1 0.007379 0.000000</div><div> -3 1 1 2 1 -0.008540 0.000000</div><div> -3 1 1 3 1 -0.008540 0.000000</div><div> -3 1 1 4 1 -0.008540 0.000000</div><div> -3 1 1 1 2 -0.008540 -0.000000</div></div><div><br></div><div><br></div><div>But as <a href="http://mailman.qe-forge.org/pipermail/wannier/2017-April/001350.html">http://mailman.qe-forge.org/pipermail/wannier/2017-April/001350.html</a> says for non-entangle case, wannierisation is robust to initial projection. As a test and for reproducibility, I choose below projection instead of random projection</div><div><br></div><div><div>f=0.0,0.0,0.0:dxy</div><div>f=0.0,0.0,0.5:dxy</div><div>f=0.0,0.5,0.0:dxy</div><div>f=0.5,0.0,0.0:dxy</div></div><div><br></div><div>conv_window and conv_tol are as previous. The convergence takes much more steps, totally 1168 steps. But the final state is the same to every digit in wout file, and xsf file visually the same in xcrysden</div><div><br></div><div><div>Final State</div><div> WF centre and spread 1 ( -0.806995, 0.806995, 0.000000 ) 0.58022874</div><div> WF centre and spread 2 ( -0.000000, 0.000000, -0.000000 ) 0.58022873</div><div> WF centre and spread 3 ( -0.806995, -0.000000, 0.806995 ) 0.58022875</div><div> WF centre and spread 4 ( -0.000000, 0.806995, 0.806995 ) 0.58022873</div><div> Sum of centres and spreads ( -1.613990, 1.613990, 1.613990 ) 2.32091495</div><div><br></div><div> Spreads (Ang^2) Omega I = 1.954626519</div><div> ================ Omega D = 0.000000000</div><div> Omega OD = 0.366288427</div><div> Final Spread (Ang^2) Omega Total = 2.320914946</div></div><div><br></div><div>However, if we look at the hr.dat this time. The content is as below</div><div><br></div><div><div> -3 1 1 1 1 0.007379 0.000000</div><div> -3 1 1 2 1 -0.007476 0.004128</div><div> -3 1 1 3 1 0.008130 -0.002616</div><div> -3 1 1 4 1 0.008218 -0.002326</div><div> -3 1 1 1 2 -0.007476 -0.004128</div><div> -3 1 1 2 2 0.007379 0.000000</div><div> -3 1 1 3 2 0.008382 0.001639</div></div><div><br></div><div>I really don't understand why such a significant imaginary parts considering that we have exactly the same wannierisation result？ Besides, I've tried many random projection all get same wannierisation, but failed to get even one clean hr.dat with zero imaginary part.</div></div>
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