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<div>Hi,</div>
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<div>I’m currently computing wave function overlap of some KS-wave functions produced by QE for monolayer MoS2 with SOC enabled. The wave functions are read with HDF5 in Fortran. However, something is bothering me. When computing </div>
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<div>< nk | nk’ > = delta_kk’ sum_{G_nk} C*_nk(G_nk) C_nk’(G_nk) ,</div>
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<div>O_nk_nk' = <span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);">sum_{G_nk} C*_nk(G_nk) C_nk’(G_nk),</span></div>
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<div>for k = (0.0 , 0.0 , 0.0) and k’ = (1/3, 1/3, 0) in crystal coordinates, and some fixed band, n (I choose the top valence band in this example), I get wildly different values depending on the k-space sampling. In the equation C_nk and C_nk’ denotes the
plane wave coefficients stored in the .hdf5 output files.</div>
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<div>I’ve attached a figure, displaying the absolute value of <font color="#000000"><span style="caret-color: rgb(0, 0, 0);">O_nk_nk’ </span></font><span style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);">for different k-space samplings.</span></div>
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<div><font color="#000000">I would have imagined, that the values of <span style="caret-color: rgb(0, 0, 0);">O_nk_nk’ </span>should either be identical or at least look smooth when plotted against the k-space sampling. Can you clarify on this behaviour?</font></div>
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<div><font color="#000000">As a note, the wave function stored in your .hdf5 files have four times the length of the number of planewaves (npw). Therefore, I rearrange the wave function as (Fortran version)</font></div>
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<div><font face="Menlo">psi_up_r = psi_k(1 :npw_ ,:),</font></div>
<div><font face="Menlo">psi_up_i = psi_k(npw_+1 :2*npw_ ,:),</font></div>
<div><font face="Menlo">psi_dw_r = psi_k(2*npw_+1 :3*npw_ ,:),</font></div>
<div><font face="Menlo">psi_dw_i = psi_k(3*npw_+1 :4*npw_ ,:),</font></div>
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<div>where r denotes the real part and vice versa for i. Moreover, I am aware that the G-basis varies for each k-point, and I took care of this as well.</div>
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<div>Attached figure: </div>
<a href="https://www.dropbox.com/s/m70kwhg0wir7eh1/wf.png?dl=0">https://www.dropbox.com/s/m70kwhg0wir7eh1/wf.png?dl=0</a>
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<div>Sorry for reposting, but I did not realise that figures should be attached externally.</div>
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<div>Kind regards<br>
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Carl Emil Mørch Nielsen<br>
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MSc. Carl Emil Mørch Nielsen<br>
Universität Hamburg<br>
HARBOR, Geb. 610<br>
Luruper Chaussee 149<br>
D-22761 Hamburg<br>
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