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<p>Hello <br>
</p>
<p>the input is generated following to the schema and expects only
lattice vectors in bohr units. <br>
</p>
<p>The presence of alat and bravais_index attributes is optional and
indicates that the cell vectors were generated with the same
algorithm used in the latgen routine. <br>
</p>
<p>In the case on ibrav = 0 cell vectors are arbitrarily defined by
the user, the routine which writes the xml file computes alat as
the modulus of the first cell vector, but it is probably better
not to write it at all.<br>
</p>
<p> In the other cases you mentioned the celldm(1) provided in
input was probably equal to the modulus of the first
cell_vector. Or celldm(1) was not provided at all in which case
alat is computed as the modulus of the first cell vector.</p>
<p>By the way in CELL PARAMETERS it is also possible to specify
angstroms as units instead of alat and avoid to use celldm(1) <br>
</p>
<p><br>
</p>
<p>thanks for reporting the case <br>
</p>
<p>best regards <br>
</p>
<p>Pietro <br>
</p>
<br>
<div class="moz-cite-prefix">On 05/10/2018 10:39, Ryky Nelson wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAMmLhK6GJpnQRhZEGk3Rn=S+Z6J_F+xMwi3nmzou8jWt+09vhQ@mail.gmail.com">
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<div class="gmail_default"
style="font-family:arial,helvetica,sans-serif;font-size:small">Hi
all,</div>
<div class="gmail_default"
style="font-family:arial,helvetica,sans-serif;font-size:small"><br>
</div>
<div class="gmail_default"
style="font-family:arial,helvetica,sans-serif;font-size:small">some
user gave me the following setup of the input file for the
namelist SYSTEM and the card CELL_PARAMETERS<br>
</div>
<div class="gmail_default"
style="font-family:arial,helvetica,sans-serif;font-size:small"><br>
</div>
<div class="gmail_default"
style="font-family:arial,helvetica,sans-serif;font-size:small"> &SYSTEM<br>
ibrav = 0,<br>
celldm(1) = 1.8897265,<br>
nat = 4,<br>
ntyp = 3,<br>
ecutwfc = 70,<br>
ecutrho = 560,<br>
nbnd = 38,<br>
/</div>
<div class="gmail_default"
style="font-family:arial,helvetica,sans-serif;font-size:small">CELL_PARAMETERS
{alat}<br>
3.124623266 -3.124623266 0.000000000<br>
-3.124623266 0.000000000 -3.124623266<br>
3.124623266 3.124623266 0.000000000<br>
</div>
<div class="gmail_default"
style="font-family:arial,helvetica,sans-serif;font-size:small"><br>
</div>
<div class="gmail_default"
style="font-family:arial,helvetica,sans-serif;font-size:small">After
finishing the calculation with QE 6.3 with the above setup,
strangely I got two alat values in data-file-schema.xml that
are different from each other; the first alat value, which is
put inside the section <input>, is 8.350483329220e0 and
the other one, which is inside <output>, is
1.889726500000e0 [which is equal to celldm(1)]. Could any one
tell me why they are different? My guess is that it has to do
with the CELL_PARAMETERS setup; since it's in {alat}, the
elements are supposed between -1 & 1, and previously, with
other cases using this [-1,1] setup in {alat}, I always got
the same alat values from the <input> &
<output> sections? But Could any one tell me the exact
reason? Thanks!</div>
<div class="gmail_default"
style="font-family:arial,helvetica,sans-serif;font-size:small"><br>
</div>
<div class="gmail_default"
style="font-family:arial,helvetica,sans-serif;font-size:small">Ryky<br>
</div>
</div>
<br>
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