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<p>Dear all, </p>
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<p>I want to do an SCF calculation on sodalite (a kind of zeolite) unit cell (consisting 36 atoms) but I'm having some difficulties to do so. First off, I don't know what the vital and least parameters needed for these types of calculations are. So I used virtual
nanolab to generate an input file. Following a tutorial on Quantum Wise website, I manipulated the input files, for instance they said to include nbnd=10, change the ecutwfc=30, etc.However, when I stared running the simulation, I kept getting an error "too
few bands". So I started increasing the number by the order of 10 (without having any idea what it is!) and at nbnd=100 my simulations is now being run. I left other variables (such as K_POINTS) unchanged. I would really appreciate it if someone would tell
me what should be and should not be in my input file for scf calculations and give me a sense of the range of numbers that I'm allowed to assign to the variables. Here is my input file: </p>
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<p><font color="#006fc9">&control<br>
</font></p>
<font color="#006fc9"> calculation = 'scf'<br>
verbosity = 'high'<br>
restart_mode = 'from_scratch'<br>
prefix = 'SOD'<br>
tstress = .false.<br>
tprnfor = .false.<br>
pseudo_dir = './'<br>
outdir = '/tmp'<br>
/<br>
<br>
&system<br>
ibrav=0<br>
nat=36<br>
ntyp=2<br>
ecutwfc=30<br>
ecutrho=300<br>
nbnd=100<br>
input_dft='PBE'<br>
/<br>
<br>
&electrons<br>
diagonalization='david'<br>
mixing_mode = 'plain'<br>
mixing_beta = 0.7<br>
conv_thr = 1.0d-08<br>
/<br>
<br>
ATOMIC_SPECIES<br>
O 15.999400 O.pbe-kjpaw.UPF<br>
Si 28.085500 Si.pbe-rrkj.UPF<br>
<br>
</font>
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<p><font color="#006fc9">ATOMIC_POSITIONS bohr <br>
</font></p>
<p><font color="#006fc9"> O 4.223852 10.209245 16.553687<br>
O 12.694549 1.738548 8.082990<br>
O 16.194639 10.209245 16.553687<br>
O 7.723942 1.738548 8.082990<br>
O 16.194639 10.209245 4.582900<br>
O 7.723942 1.738548 13.053597<br>
O 4.223852 10.209245 4.582900<br>
O 12.694549 1.738548 13.053597<br>
O 16.194639 4.223852 10.568293<br>
O 7.723942 12.694549 19.038991<br>
O 16.194639 16.194639 10.568293<br>
O 7.723942 7.723942 2.097596<br>
O 4.223852 16.194639 10.568293<br>
O 12.694549 7.723942 2.097596<br>
O 4.223852 4.223852 10.568293<br>
O 12.694549 12.694549 2.097596<br>
O 10.209245 16.194639 4.582900<br>
O 1.738548 7.723942 13.053597<br>
O 10.209245 16.194639 16.553687<br>
O 1.738548 7.723942 8.082990<br>
O 10.209245 4.223852 16.553687<br>
O 1.738548 12.694549 8.082990<br>
O 10.209245 4.223852 4.582900<br>
O 1.738548 12.694549 13.053597<br>
Si 5.973897 10.209245 19.038991<br>
Si 14.444594 1.738548 10.568293<br>
Si 14.444594 10.209245 2.097596<br>
Si 5.973897 1.738548 10.568293<br>
Si 1.738548 5.973897 10.568293<br>
Si 10.209245 14.444594 19.038991<br>
Si 1.738548 14.444594 10.568293<br>
Si 10.209245 5.973897 2.097596<br>
Si 10.209245 1.738548 6.332945<br>
Si 1.738548 10.209245 14.803642<br>
Si 10.209245 1.738548 14.803642<br>
Si 1.738548 10.209245 6.332945<br>
<br>
K_POINTS gamma<br>
<br>
CELL_PARAMETERS bohr<br>
17.933187 0.000000 0.000000<br>
0.000000 17.933187 0.000000<br>
0.000000 0.000000 21.136587 </font>
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<p>Best regards,<br>
</p>
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<div id="Signature">
<div id="divtagdefaultwrapper" style="font-size:12pt; color:#000000; background-color:#FFFFFF; font-family:Calibri,Arial,Helvetica,sans-serif">
<p>Amir M. Mofrad<span> </span></p>
<p>Graduate Research Assistant <span> </span></p>
<p>Chemical Engineering Department</p>
<p>University of Missouri<br>
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