[Pw_forum] About Xspectra using USPP

[Huang, Xu]

Hi all,


I'm learning how to use QE to plot K-edge X-ray spectra for hematite (Fe2O3). I'm looking at the examples of NiO using norm-conserved pseudopotential (NCPP) and SiO2 using ultrasoft pseudopotential (USPP). As transition metal oxides, Fe2O3 is similar with NiO xspectra calculation that needs scf, dip, dip_replot and qua steps. The SiO2 example doesn't have qua part, but it has some restart steps: scf, dip_plane, dip_c, dip_restart_1 and dip_restart_2. So my questions are:


1. Are those extra "restart" steps required in the calculation using USPP? For the qua step of Fe2O3, should I add those "restart" steps, too?


2. The main difference in the scripts using NMPP and USPP is that the wf_collet is always set to be .ture. in USPP script. Is that another required thing for USPP calculation?


3. For SiO2, what's the difference between the dip_plane and dip_c steps? Is it system-specific? What type of system should involve those different dip calculations?


Thank you,

Xu Huang


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