<html><body><div style="color:#000; background-color:#fff; font-family:bookman old style, new york, times, serif;font-size:14pt"><div><span style="font-size: 13px;">Thank you so much dear Dr. Blaha and Dr. Jorissen for your useful comments.</span></div><div style="color: rgb(0, 0, 0); font-size: 13px; font-family: 'bookman old style', 'new york', times, serif; font-style: normal; background-color: transparent;"><span style="font-size: 13px;"><br></span></div><div style="color: rgb(0, 0, 0); font-size: 13px; font-family: 'bookman old style', 'new york', times, serif; font-style: normal; background-color: transparent;"><span style="font-size: 13px;">Best wishes</span></div><div><br></div> <div style="font-family: 'bookman old style', 'new york', times, serif; font-size: 14pt;"> <div style="font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; font-size: 12pt;"> <div dir="ltr"> <hr size="1"> <font size="2"
face="Arial"> <b><span style="font-weight:bold;">From:</span></b> Peter Blaha <pblaha@theochem.tuwien.ac.at><br> <b><span style="font-weight: bold;">To:</span></b> A Mailing list for WIEN2k users <wien@zeus.theochem.tuwien.ac.at> <br> <b><span style="font-weight: bold;">Sent:</span></b> Wednesday, August 27, 2014 12:11 AM<br> <b><span style="font-weight: bold;">Subject:</span></b> Re: [Wien] QTL-B error for Zn K-edge ELNES<br> </font> </div> <div class="y_msg_container"><br>About core-hole calculations for XSPEC or TELNES:<br><br>1) You need to make a sizable supercell !!! Maybe start with 16 <br>atoms/cell, but 64 or more are even better. It is WRONG to make a <br>core-hole calculation with just 2 Zn atoms/cell. Why: Consider reality: <br>You excite only VERY few atoms in such a measurements (actually VERY few <br>even means 1 out of 10^10 or less!!!), the majority of atoms remain in <br>the ground state and can contribute to the screening.
This is, what we <br>want to simulate.<br><br>2) We need to have charge neutrality, i.e. the sum of nuclear charges <br>and electronic charges must cancel. By removing 1 e- from one atom in <br>the cell, you need to add this charge somewhere. 2 possibilities:<br>a) add it as valence electron (increase NE in case.in2; but don't forget <br>to remove this e- AFTER the scf cycle and before calculation the spectra)<br>b) add a background charge in case.inm.<br>MSR1 -1.0 YES (BROYD/PRATT, extra charge (+1 for additional e), norm)<br>As the comment says, you should set this value to +1, when you have <br>added an e-. For core holes, we have REMOVED an electron, thus we must <br>set this to -1.0 !!!<br>You SHOULD ALWAYS CHECK your charge neutrality using<br>grep :NEC01 case.scf.<br><br>Now which method is better, a) or b) ???<br>In many cases there is NOT much difference, though in some cases there <br>could be a
difference.<br>Again, remember we want to simulate experiment as close as possible:<br>the Zn 1s electron will be excited (dipole rule) into Zn-4p electrons. <br>The electronic structure of ZnO has mainly Zn-s and p character at the <br>conduction band minimum, thus when we use method b), we actually add <br>this e- into Zn-s+p states, which is "approximately" correct. However, <br>since the Zn-4sp states are very delocalized states with little weight <br>inside the Zn-sphere, I don't think it matters too much when you put the <br>charge into the background.<br>An opposite example would be eg. CeO2, which has very localized Ce-4f <br>states just above EF. When simulating O-K edges, it is NOT a good idea <br>to add the e- into the valence, because it will go into LOCALIZED Ce-4f <br>states and not contribute significantly to screen the core-hole on <br>oxygen. The method b) would be better in this case. Of course, for Ce-M <br>edges obviously method a)
should be much better.<br><br>Hope this clarifies the unclear discussion on the mailing list.<br><br>Peter Blaha<br><br>-------------------------------<br>Subject: Re: [Wien] QTL-B error for Zn K-edge ELNES<br>From: Paul Fons <<a ymailto="mailto:paul-fons@aist.go.jp" href="mailto:paul-fons@aist.go.jp">paul-fons@aist.go.jp</a>><br>Date: 08/27/2014 06:37 AM<br>To: A Mailing list for WIEN2k users <<a ymailto="mailto:wien@zeus.theochem.tuwien.ac.at" href="mailto:wien@zeus.theochem.tuwien.ac.at">wien@zeus.theochem.tuwien.ac.at</a>><br>Hi Kevin,<br> Are you sure you are correct for using "-1" in case.inm. I can <br>reproduce the example from the Wien2K course (MgO supercell) just fine <br>when I use a "+1" in case.inm. The documentation states that "1" adds <br>another electron. From what I understand this is to compensate for the <br>electron that is removed when a core hole is generated by changing the
<br>occupancy in case.inc. For the case of MgO.inc<br><br> 1 0.00 0 NUMBER OF ORBITALS (EXCLUDING SPIN), SHIFT, IPRINT<br>1,-1,2 ( N,KAPPA,OCCUP)<br> 1 0.00 0 NUMBER OF ORBITALS (EXCLUDING SPIN), SHIFT, IPRINT<br>1,-1,2 ( N,KAPPA,OCCUP)<br> 1 0.00 0 NUMBER OF ORBITALS (EXCLUDING SPIN), SHIFT, IPRINT<br>1,-1,2 ( N,KAPPA,OCCUP)<br> 1 0.00 0 NUMBER OF ORBITALS (EXCLUDING SPIN), SHIFT, IPRINT<br>1,-1,2 ( N,KAPPA,OCCUP)<br> 1 0.00 0 NUMBER OF ORBITALS (EXCLUDING SPIN), SHIFT, IPRINT<br>1,-1,2 ( N,KAPPA,OCCUP)<br> 0<br><br><br> I changed the second line to 1,-1,1 to make a core hole. I then <br>compensated
for the missing charge with case.inm to add a +1 background <br>charge via<br><br>MSR1 1.0 YES (BROYD/PRATT, extra charge (+1 for additional e), norm)<br>0.20 mixing FACTOR for BROYD/PRATT scheme<br>1.00 1.00 PW and CLM-scaling factors<br>9999 8 idum, HISTORY<br><br>After this, I run a SCF calculation. When it is done, I then remove the <br>charge from case.inm and carry out a XSPEC calculation. This is what I <br>learned in the Wien2K course a couple of years ago when the developers <br>had a seminar here in Japan. As I mentioned, the above procedure <br>reproduces the MgO core hole present plot in the exercise notes. I <br>would be very much interested in hearing if I am doing something incorrect.<br><br>Cheers,<br>Paul<br><br><br><br><br>-- <br><br>
P.Blaha<br>--------------------------------------------------------------------------<br>Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna<br>Phone: +43-1-58801-165300 FAX: +43-1-58801-165982<br>Email: <a ymailto="mailto:blaha@theochem.tuwien.ac.at" href="mailto:blaha@theochem.tuwien.ac.at">blaha@theochem.tuwien.ac.at</a> WWW: <br><a href="http://info.tuwien.ac.at/theochem/" target="_blank">http://info.tuwien.ac.at/theochem/</a><br>--------------------------------------------------------------------------<br>_______________________________________________<br>Wien mailing list<br><a ymailto="mailto:Wien@zeus.theochem.tuwien.ac.at" href="mailto:Wien@zeus.theochem.tuwien.ac.at">Wien@zeus.theochem.tuwien.ac.at</a><br><a href="http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien"
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