Hello Peng,<div><br></div><div>One can compute U for the AFM and FM states separately using linear response. Then, using the calculated U values for each state, you can recompute the gaps. This approach might resolve the issue.</div>
<div><br></div><div>Best regards,</div><div><br></div><div>Burak<br><br><div class="gmail_quote">On Wed, Aug 8, 2012 at 1:00 PM, Peng Chen <span dir="ltr"><<a href="mailto:pchen@ion.chem.utk.edu" target="_blank">pchen@ion.chem.utk.edu</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div>Dear All,</div><div><br></div><div>According to the experiments, the material's ground state is afm and the band gap is ~2.30 eV in 4K. </div>
<div>In the magnetic field, the spin moments are aligned in the field direction (we call it "fm state") and the </div>
<div>band gap is ~2.34 eV. But from the calculation results, when U>=5 eV, the fm spin up gap is less </div><div>than that of afm state which is different from experimental results. (I guess we should choose spin </div>
<div>up gap to represent fm state gap since spin down gap is larger). From the calculated gap value, </div><div>U=8 eV is close to experimental results, but the gap in fm state is less. Please let me know what </div><div>
I can do to improve the results?</div>
<div><br></div><div><br></div><div>U afm gap fm spin up fm spin down </div><div>4 1.49 1.723 1.731 </div><div>5 1.81 1.77 2.01</div>
<div>6 1.922 1.912 2.273</div><div>8 2.265 2.076 2.634</div><span class="HOEnZb"><font color="#888888"><br clear="all"><div><br></div>-- <br> Best Regards.<br> Peng <br>
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