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<p>Hi,</p>
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<p>It is recommended (but not mandatory) to do first a GGA calculation before using GGA+U or mBJ. By doing so, the starting electron density for the GGA+U/mBJ SCF iterations may be better than the one from init_lapw (lstart/dstart) in order to reduce the number
of iterations and/or to reach the proper ground state. </p>
<p>It may also be a good idea (but again not mandatory) to start a mBJ calculation using the GGA+U electron density.</p>
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<p>FT</p>
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<div id="divRplyFwdMsg" dir="ltr"><font color="#000000" face="Calibri, sans-serif" style="font-size: 11pt;"><b>From:</b> Wien <wien-bounces@zeus.theochem.tuwien.ac.at> on behalf of shamik chakrabarti <shamik15041981@gmail.com><br>
<b>Sent:</b> Sunday, March 8, 2020 10:09 AM<br>
<b>To:</b> A Mailing list for WIEN2k users<br>
<b>Subject:</b> [Wien] confusion with GGA+U and mbj</font>
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<div dir="ltr">Dear Wien2k users,
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<div> If simulation of a material is to run with GGA+U to get an approximate band gap, then
<b>whether GGA+U or GGA</b> has to run as a first step for running mbj?</div>
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<div>As user guide says that we have to run a normal SCF prior to mbj, my confusion is whether the normal SCF is to run with GGA or GGA+U if U is mandatory for the material.</div>
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<div>Looking forward to your response in this regard.</div>
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<div>with regards,<br clear="all">
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<div style="font-size: small;">Dr. Shamik Chakrabarti</div>
<div style="font-size: small;">Research Fellow </div>
<div style="font-size: small;">Department of Physics</div>
<div style="font-size: small;">Indian Institute of Technology Patna</div>
<div style="font-size: small;">Bihta-801103</div>
<div style="font-size: small;">Patna</div>
<div style="font-size: small;">Bihar, India</div>
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