<div dir="ltr"><div>Dear Prof Peter,<br><br></div>Please comment of my query when you get time:This is in the queue on my previous query regarding CH3NH3PbI3:<br><div><div><div><div class="gmail_extra"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div><div><div><div><div><div><br></div>I used two strategy and got different results:<br><br><br><font color="#000000">The experimental band gap
is 1.67 eV for orthorhombic lead halide perovskite.<br></font><br><div>I ran two cases (with PBE);<br>
</div>
1. with 1000 k, div: ( 11 7 11) and "min -j 'run_lapw -p
-I -NI -i 120 <b><span style="color:rgb(0,0,255)">-ec </span></b>0.00001 <b><span style="color:rgb(0,0,255)">-ec </span></b> 0.0001 -fc 1<br clear="all">
<div dir="ltr"><font color="#000000">2. with 400
k, div: ( 8 5 8) and min -j 'run_lapw
-p -I -NI -i 120 </font><font color="#000000"><b><span style="color:rgb(0,0,255)">-ec </span></b> 0.0001 </font><font color="#000000"><b><span style="color:rgb(0,0,255)">-ec </span></b> 0.0005 -fc 2'<br></font></div></div></div></div></div></div></div></blockquote><div><font color="#000099"><span style="color:rgb(0,0,0)">-ec switch is used twice instead of ec and cc (it is by mistake)</span></font> <br></div><div>In case 2 with less k-points and normal scf
criteria (<span style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)"><span style="color:rgb(0,0,255)">-ec</span></span>
0.0001 <span style="color:rgb(0,0,255)">-ec</span> 0.0005 -fc 2), I got minimized ENE
than case 1. But the band gap is good from
case 1.<br><br></span><br><div dir="ltr"><font color="#000000">Results:</font></div>
<div dir="ltr"><font color="#000000"><br>
</font></div>
<div dir="ltr"><font color="#000000">1. GAP 1.687
eV, FER: 0.1030934295,
ENE: -339059.11079128</font></div>
<div dir="ltr"><font color="#000000">2. GAP 1.777
eV, FER: 0.1004906191, ENE: -339059.12432403<br></font><br><font color="#000000">You see that band gap is in the error of /+- 0.01eV.<br></font></div> <br><b>[* next i tried with <br><br>1. with 1000 k, div: ( 11 7 11) and "min -j 'run_lapw -p
-I -NI -i 120 <span style="color:rgb(0,0,255)">-ec </span>0.00001 <span style="color:rgb(0,0,255)"><u>-cc</u> </span> 0.0001 -fc 1 >> second -ec is replaced by -cc<br clear="all">
<font color="#000000">2. with 400
k, div: ( 8 5 8) and min -j 'run_lapw
-p -I -NI -i 120 </font><font color="#000000"><span style="color:rgb(0,0,255)">-ec </span> 0.0001 </font><font color="#000000"><u><span style="color:rgb(0,0,255)">-<font color="#000000">c</font>c </span></u> 0.0005 -fc 2' </font></b><b><font color="#000000"><b>>> second -ec is replaced by -cc</b><br></font></b></div><div><b><font color="#000000">and nothing happened scf immediately got exit and the structure was already optimized]</font></b></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div><div><div><div><br></div><br></div>I did nothing special, just reduced rmt (5% and further rmt of "I" was reduced by 0.02).<br><i><u>Please correct me what is wrong here. Because usually PBE always underestimates the experimental band gap.</u></i><br><br></div>Kind regards<span class="gmail-HOEnZb"><font color="#888888"><br></font></span></div><span class="gmail-HOEnZb"><font color="#888888">Bhamu</font></span></div>
</blockquote></div><br></div></div></div></div></div>