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<p>Hi <br>
</p>
<p>the last one is probably the calculation done at the end of the
vc-relax calculation with reinitialized plane wave basis set. <br>
</p>
<p>It might be that, because of the lower cutoff the relaxation with
the PAWs is more affected by the non reinitialized basis set. <br>
</p>
<p>You could simply increase the cutoff in the relaxation using PAW
, or try to use the ecfixed, qcutz and q2sigma variables, to
reduce the number of plane waves. <br>
</p>
<p>hope it helps <br>
</p>
<p>Pietro<br>
</p>
<div class="moz-cite-prefix">On 24/09/20 09:39, mkondrin wrote:<br>
</div>
<blockquote type="cite" cite="mid:5F6C4D4F.4020602@hppi.troitsk.ru">Dear
developers and users,
<br>
<br>
I have encountered strange results while trying to relax simple
sphalerite structure of ZnSe using PAW pseudopotentials from
official site. I am starting from experimental lattice constant at
zero pressure but the calculated stress was large and negative.
The subsequent calculation converges to zero pressure but the
final step also produces the large negative stress.
<br>
<br>
$grep stress bulk1.out
<br>
Computing stress (Cartesian axis) and pressure
<br>
total stress (Ry/bohr**3) (kbar) P=
-368.58
<br>
Computing stress (Cartesian axis) and pressure
<br>
total stress (Ry/bohr**3) (kbar)
P= 112.26
<br>
Computing stress (Cartesian axis) and pressure
<br>
total stress (Ry/bohr**3) (kbar)
P= 23.80
<br>
Computing stress (Cartesian axis) and pressure
<br>
total stress (Ry/bohr**3) (kbar)
P= -3.11
<br>
Computing stress (Cartesian axis) and pressure
<br>
total stress (Ry/bohr**3) (kbar)
P= 3.52
<br>
Computing stress (Cartesian axis) and pressure
<br>
total stress (Ry/bohr**3) (kbar)
P= -5.37
<br>
Computing stress (Cartesian axis) and pressure
<br>
total stress (Ry/bohr**3) (kbar)
P= 2.61
<br>
Computing stress (Cartesian axis) and pressure
<br>
total stress (Ry/bohr**3) (kbar)
P= -0.40
<br>
Computing stress (Cartesian axis) and pressure
<br>
total stress (Ry/bohr**3) (kbar) P=
-268.92
<br>
<br>
I have also tried ONCV pseudopotential (with larger cutoffs 70 Ry
of course) and the result is quite different -- the calculated
total stress is small (22 kbar) and it rapidly and monotonically
converges to zero.
<br>
<br>
I am using QE-6.4.
<br>
<br>
Sincerely yours,
<br>
M. V. Kondrin
<br>
<br>
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