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<div class="moz-cite-prefix">On 06/09/2017 11:22, Charlie Ruffman
wrote:<br>
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<p>Hi all, </p>
<p><br>
</p>
<p>I have recently become interested in how the size of the unit
cell in phonon calculations effects the results produced by
the calculation (Raman spectra in particular). It seems that
increasing the number of atoms
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explicitly </span>simulated should also increase the number
of normal modes calcuated? </p>
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It does. these are hovewer modes that would correspond to a q/=0 in
the original primitive cell... as such they should be
raman-inactive.<br>
The calculation in the supercell, if properly done (same cutoff,
equivalent k-points, sufficient scf convergence) should be exactly
comparable to the superposition of the results in the primitive cell
for the q-vectors that map into the Gamma point of the supercell.<br>
<br>
stefano<br>
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<p>Does anyone know if using the primitive cell will produce
more or less accurate results than a larger supercell?</p>
<p><br>
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<p>Thanks</p>
<p><br>
</p>
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<div style="font-family:Calibri,Arial,Helvetica,sans-serif;
font-size:16px"><span style="color:rgb(34,34,34);
font-size:9pt; font-family:"Times New
Roman",serif">Charlie Ruffman | <span
style="color:rgb(31,78,121)">BSc<br>
</span></span><span style="color:rgb(31,78,121);
font-family:"Times New Roman",serif;
font-size:12px">BSc(Hons) </span><span
style="color:rgb(34,34,34); font-size:9pt;
font-family:"Times New Roman",serif"><span
style="color:rgb(31,78,121)">Student<br>
</span><br>
<span style="color:rgb(31,78,121)">Chemistry Department<br>
University of Otago</span> <span
style="color:rgb(59,56,56)"><br>
</span><span style="color:rgb(31,78,121)">Tel</span> 64
3 479 7930<br>
<span style="color:rgb(31,78,121)">PO Box 56, Dunedin
9054</span><br>
<span style="color:rgb(31,78,121)">New Zealand</span> <br>
<br>
<span style="color:rgb(31,78,121)">Website</span> </span><font
style="font-size:12.8px" color="#0000ff" face="Times New
Roman, serif"><span style="font-size:12px"><u><a
href="http://neon.otago.ac.nz/research/alg/"
target="_blank" id="LPNoLP"
style="color:rgb(17,85,204)"
moz-do-not-send="true">http://neon.otago.ac.<wbr>nz/research/alg/</a></u></span></font></div>
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