Hi, 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
< nk | nk’ > = delta_kk’ sum_{G_nk} C*_nk(G_nk) C_nk’(G_nk) , O_nk_nk' = sum_{G_nk} C*_nk(G_nk) C_nk’(G_nk), 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. I’ve attached a figure, displaying the absolute value of O_nk_nk’ for different k-space samplings. I would have imagined, that the values of O_nk_nk’ should either be identical or at least look smooth when plotted against the k-space sampling. Can you clarify on this behaviour? 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) psi_up_r = psi_k(1 :npw_ ,:), psi_up_i = psi_k(npw_+1 :2*npw_ ,:), psi_dw_r = psi_k(2*npw_+1 :3*npw_ ,:), psi_dw_i = psi_k(3*npw_+1 :4*npw_ ,:), 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. Attached figure: https://www.dropbox.com/s/m70kwhg0wir7eh1/wf.png?dl=0 Sorry for reposting, but I did not realise that figures should be attached externally. Kind regards Carl Emil Mørch Nielsen --------------------------------------------------------- MSc. Carl Emil Mørch Nielsen Universität Hamburg HARBOR, Geb. 610 Luruper Chaussee 149 D-22761 Hamburg ---------------------------------------------------------
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