<div dir="ltr">Hi Everyone,<div>I am doing a single-point calculation on a 1D polymer in QE using PBE-PAW. However, I am seeing an issue in the SCF iteration cycles. The first iteration seems to print the right electronic energy but from iteration 2 the energy suddenly increases significantly and then the SCF ends up with higher energy. I am a little confused about how to stabilize the SCF iteration so the energy does not go up. Any suggestions will be highly appreciated. </div><div><br></div><div>I am providing the output of the first three iterations of the SCF for deep insights.</div><div><br></div><div>------------------------------------------------------------------------------</div><div><p style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"><span class="gmail-Apple-converted-space"> </span>iteration #<span class="gmail-Apple-converted-space"> </span>1 <span class="gmail-Apple-converted-space"> </span>ecut= <span class="gmail-Apple-converted-space"> </span>120.00 Ry <span class="gmail-Apple-converted-space"> </span>beta= 0.30</span></p>
<p style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"><span class="gmail-Apple-converted-space"> </span>Davidson diagonalization with overlap</span></p>
<p style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"><span class="gmail-Apple-converted-space"> </span>ethr =<span class="gmail-Apple-converted-space"> </span>1.00E-02,<span class="gmail-Apple-converted-space"> </span>avg # of iterations =<span class="gmail-Apple-converted-space"> </span>2.0</span></p>
<p style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"><span class="gmail-Apple-converted-space"> </span>negative rho (up, down):<span class="gmail-Apple-converted-space"> </span>1.348E-04 0.000E+00</span></p>
<p style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"><span class="gmail-Apple-converted-space"> </span>total cpu time spent up to now is <span class="gmail-Apple-converted-space"> </span>13.7 secs</span></p>
<p style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"><span class="gmail-Apple-converted-space"> </span></span><span style="font-variant-ligatures:no-common-ligatures;background-color:rgb(224,228,9)">total energy</span><span style="font-variant-ligatures:no-common-ligatures"><span class="gmail-Apple-converted-space"> </span>=<span class="gmail-Apple-converted-space"> </span>-304.41586797 Ry</span></p>
<p style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"><span class="gmail-Apple-converted-space"> </span>estimated scf accuracy<span class="gmail-Apple-converted-space"> </span>< <span class="gmail-Apple-converted-space"> </span>2.72932626 Ry</span></p>
<p style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"><span class="gmail-Apple-converted-space"> </span>iteration #<span class="gmail-Apple-converted-space"> </span>2 <span class="gmail-Apple-converted-space"> </span>ecut= <span class="gmail-Apple-converted-space"> </span>120.00 Ry <span class="gmail-Apple-converted-space"> </span>beta= 0.30</span></p>
<p style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"><span class="gmail-Apple-converted-space"> </span>Davidson diagonalization with overlap</span></p>
<p style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"><span class="gmail-Apple-converted-space"> </span>ethr =<span class="gmail-Apple-converted-space"> </span>3.79E-03,<span class="gmail-Apple-converted-space"> </span>avg # of iterations =<span class="gmail-Apple-converted-space"> </span>1.0</span></p>
<p style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"><span class="gmail-Apple-converted-space"> </span>negative rho (up, down):<span class="gmail-Apple-converted-space"> </span>1.006E-04 0.000E+00</span></p>
<p style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"><span class="gmail-Apple-converted-space"> </span>total cpu time spent up to now is <span class="gmail-Apple-converted-space"> </span>16.3 secs</span></p>
<p style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"><span class="gmail-Apple-converted-space"> </span></span><span style="font-variant-ligatures:no-common-ligatures;background-color:rgb(224,228,9)">total energy</span><span style="font-variant-ligatures:no-common-ligatures"><span class="gmail-Apple-converted-space"> </span>=<span class="gmail-Apple-converted-space"> </span>-304.13553253 Ry</span></p>
<p style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"><span class="gmail-Apple-converted-space"> </span>estimated scf accuracy<span class="gmail-Apple-converted-space"> </span>< <span class="gmail-Apple-converted-space"> </span>0.76532583 Ry</span></p>
<p style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"><span class="gmail-Apple-converted-space"> </span>iteration #<span class="gmail-Apple-converted-space"> </span>3 <span class="gmail-Apple-converted-space"> </span>ecut= <span class="gmail-Apple-converted-space"> </span>120.00 Ry <span class="gmail-Apple-converted-space"> </span>beta= 0.30</span></p>
<p style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"><span class="gmail-Apple-converted-space"> </span>Davidson diagonalization with overlap</span></p>
<p style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"><span class="gmail-Apple-converted-space"> </span>ethr =<span class="gmail-Apple-converted-space"> </span>1.06E-03,<span class="gmail-Apple-converted-space"> </span>avg # of iterations =<span class="gmail-Apple-converted-space"> </span>6.0</span></p>
<p style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"><span class="gmail-Apple-converted-space"> </span>negative rho (up, down):<span class="gmail-Apple-converted-space"> </span>5.328E-05 0.000E+00</span></p>
<p style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"><span class="gmail-Apple-converted-space"> </span>total cpu time spent up to now is <span class="gmail-Apple-converted-space"> </span>19.4 secs</span></p>
<p style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"><span class="gmail-Apple-converted-space"> </span></span><span style="font-variant-ligatures:no-common-ligatures;background-color:rgb(224,228,9)">total energy</span><span style="font-variant-ligatures:no-common-ligatures"><span class="gmail-Apple-converted-space"> </span>=<span class="gmail-Apple-converted-space"> </span>-304.26340272 Ry</span></p>
<p style="margin:0px;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"><span class="gmail-Apple-converted-space"> </span>estimated scf accuracy<span class="gmail-Apple-converted-space"> </span>< <span class="gmail-Apple-converted-space"> </span>0.08826578 Ry</span></p>
--------------------------------------------------------------------------------------------</div><div><br></div><div>Thanks</div><div>Rameswar Bhattacharjee</div><div>Georgetown University</div></div>