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<body class='hmmessage'><div dir='ltr'>Dear All,<div><br></div><div>After performing the geometry optimization twice, I am still getting negative phonon dispersion.</div><div><span style="font-size: 12pt;"><br></span></div><div><span style="font-size: 12pt;"><br></span></div><div><span style="font-size: 12pt;">For first geometry optimization I used following tags</span></div><div><br></div><div>calculation = 'vc-relax'</div><div> </div><div><span style="font-size: 12pt;">ion_dynamics = 'bfgs'</span></div><div><span style="font-size: 12pt;"><br></span></div><div><span style="font-size: 12pt;">cell_dofree = 'shape' </span></div><div><span style="font-size: 12pt;"><br></span></div><div><span style="font-size: 12pt;"><br></span></div><div><span style="font-size: 12pt;">And for second time I used following tags</span></div><div><span style="font-size: 12pt;"><br></span></div><div>calculation<span style="font-size: 12pt;"> = vc-relax'</span></div><div><span style="font-size: 12pt;"><br></span></div><div><span style="font-size: 12pt;">ion_dynamics = 'bfgs'</span></div><div><span style="font-size: 12pt;"><br></span></div><div><span style="font-size: 12pt;">cell_dofree = '2Dxy' </span></div><div><br></div><div><br></div><div>The system I am working on is a 2D buckled tin, can someone help me out and inform me as how should one proceed with</div><div><br></div><div>geometry optimization. For Phonon Dispersion calculation I have used phonon package induced in QE as well as phononpy.</div><div><br></div><div>I have also included my input file, please check the attachment for the same.</div><div><br></div><div> </div><div><br></div><div>Regards,</div><div><br></div><div>Ghadiyali Mohammed Kader.</div> </div></body>
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