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<p>Dear Quantum Espresso,<br>
</p>
<p><br>
</p>
<p>I am trying to run a test simulation on the silicon unit cell using vc-relax. When I run the simulation using "ibrav=2" the simulation converges in 4 scf cycles. However, when I attempt to run the simulation using "ibrav = 0" it doesn't converge in 18 scf
cycles. Moreover, I always receive the error that I need to use a larger cell factor. Finally, and when using a larger cell factor, the simulation runs longer and doesn't converge and also gives me the same error again.<br>
</p>
<p>I am using this test because I will need to run vc-relax in a situation where I will need to use "ibrav=0" so it is important to me that I get it to work properly.<br>
</p>
<p>I have attached my input file below. <span style="font-size: 12pt;">Any clarifications on this is</span><span style="font-size: 12pt;">sue would be greatly appreciated.</span></p>
<p><span style="font-size: 12pt;"><br>
</span></p>
<pre style="word-wrap: break-word; white-space: pre-wrap;"> &control
calculation = 'vc-relax'
restart_mode = 'from_scratch'
prefix = 'si'
tprnfor = .true.
wf_collect = .true.
pseudo_dir = '/usr/local/espresso/espresso-5.0.3/pseudo/'
outdir = '/fs/lustre/osu7834/si/'
/
&system
ibrav = 0
nat = 2
ntyp = 1
ecutwfc = 25.0
/
&electrons
conv_thr = 1.0d-7
diagonalization = 'cg'
/
&IONS
/
&CELL
cell_factor = 1.6
/
CELL_PARAMETERS {bohr}
10.40 0.00 0.00
0.00 10.40 0.00
0.00 0.00 10.40
ATOMIC_SPECIES
Si 28 Si.pbe-n-van.UPF
ATOMIC_POSITIONS {crystal}
Si -0.25 0.75 -0.25
Si 0.00 0.00 0.00
K_POINTS {automatic}
4 4 4 0 0 0<br></pre>
<p><span style="font-size: 12pt;"><br>
</span></p>
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<p style="font-size:13px; font-family:Tahoma">+++++++++++++++++++++++++++++++++<br>
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<p style="font-size:13px; font-family:Tahoma">Adib Samin, PhD</p>
<p style="font-size:13px; font-family:Tahoma">Postdoctoral Researcher</p>
<p style="font-size:13px; font-family:Tahoma">The Department of Aerospace and Mechanical Engineering</p>
<p style="font-size:13px; font-family:Tahoma">The Ohio State University </p>
<p style="font-size:13px; font-family:Tahoma"> <br>
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