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<p class="MsoNormal">Hello everybody,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">After recently attending the QE workshop at Penn State, I have been trying to use QE to fully optimize organic structures. I did not have any issues trying to fully optimize oxalic acid (a small organic molecule) and its related dihydrate.
However, I have been trying to get naphthalene and durene (aromatic hydrocarbons) to run but have had significant issues with decreasing volume with no vdW correction implemented. Naphthalene has a published 5 K structure, so any decrease in volume is unphysical,
and I regularly see an almost 100 Ang^3 decrease in volume (~30 % decrease).<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Here are all of the things I have tried:<o:p></o:p></p>
<p class="MsoNormal">Normconserving, US, and PAW pseudo potentials <o:p></o:p></p>
<p class="MsoNormal">Increasing the cutoffs to high values (up to 150/1500 Ry)<o:p></o:p></p>
<p class="MsoNormal">Varying the number of k-points<o:p></o:p></p>
<p class="MsoNormal">Various GGA functionals (PBE, PBESOL, BLYP)<o:p></o:p></p>
<p class="MsoNormal">Using coordinates from a ‘relax’ calculation for ‘vc-relax’ calculations<o:p></o:p></p>
<p class="MsoNormal">Using optimized coordinates to do a ‘vc-relax’ calculation while holding volume constant (‘cell_dofree=shape’), and then trying a full ‘vc-relax’ calculation<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I am new to PW and QE, so maybe I am doing something simple incorrectly. Any insight would be greatly appreciated. I am attaching the INPUT, OUTPUT of the most recent naphthalene BLYP test, and the published CIF files for reference.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thank you very much in advance,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Michael Ruggiero<o:p></o:p></p>
<p class="MsoNormal">Syracuse University Chemistry<o:p></o:p></p>
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