Hello everyone, <div><br /></div><div>I'm unsure if this is the right place to post this issue as I am using phonopy to generate phonons with CP2K, however I thought I might have a bit more luck finding someone with experience using phonopy specifically with CP2K. The issue I'm having is large negative phonon modes, and large drift force reported by phonopy in the y direction (~0.25 eV/A). I know that I shouldn't be getting negative modes as my structure is certainly dynamically stable. my workflow is as follows:</div><div><br /></div><div><font size="1">phonopy --cp2k -d --dim="6 6 2" -c energy.inp <br /><br />for i in energy-supercell-*; do<br /> bn=${i%.*} # Remove file extension<br /> num=${bn#*supercell-} # Extract the number after 'energy-supercell-'<br /><br /> if [[ -z ${num} ]]; then<br /> continue<br /> fi<br /> dir="$num"<br /><br /> if [[ -d $dir ]]; then<br /> echo "Skipping: Directory $dir already exists."<br /> continue # Skip to the next iteration instead of exiting<br /> fi<br /><br /> mkdir "$dir"<br /><br /> mv "$i" "$dir/energy.inp"<br /> # if [[ "$dir" != "001" ]]; then # Keep Wavefunction file from first simulation to make others quicker<br /> # cp 001/MIN-supercell-001-RESTART.wfn "$dir/MIN-supercell-$num-RESTART.wfn"<br /># fi<br /><br /> cd "$dir"<br /> srun cp2k.psmp -i energy.inp -o result.out<br /> cd ../<br /><br />done<br /><br />phonopy --cp2k -f $(for i in {1..13}; do printf "%03d/MIN-supercell-%03d-forces-1_0.xyz " $i $i; done)<br /><br />phonopy --cp2k -c energy.inp -p -s --dim="6 6 2" --band " 0.0 0.0 0.0 0.0 0.0 0.5 0.0 0.5 0.5 0.0 0.5 0.0 0.5 0.5 0.0 0.5 0.0 0.0 0.5 0.0 0.5 0.5 0.5 0.5" --mesh 41 41 41</font></div><div><br /></div><div><br /></div><div>I have tried various supercell sizes, and have found that 4x4x2 should be more than converged enough. My energy.inp file has the coordinates of the relaxed unitcell printed as follows:<br /> &CELL<br /> A 3.870961 0 0<br /> B 0 3.9540005 0<br /> C 0 0 11.8602555<br /> PERIODIC XYZ<br /> &END CELL<br /> &COORD<br />Ba 1.9354787033 1.9770037827 9.6771343800<br />Ba 1.9354787999 1.9770022809 2.1442401159<br />Y 1.9354802394 1.9770060545 5.8953066752<br />Cu -0.0000006631 0.0000091908 7.6100822750<br />Cu -0.0000006426 0.0000055768 4.1724491018<br />Cu -0.0000078256 0.0000008848 -0.0048129326<br />O -0.0000004062 1.9770007276 -0.0014139445<br />O 1.9354801904 0.0000011797 7.3249015553<br />O 1.9354801707 0.0000009008 4.4580654293<br />O -0.0000001259 1.9770034877 7.3279693035<br />O -0.0000001304 1.9770024288 4.4553471390<br />O -0.0000006180 0.0000004257 9.9643054004<br />O -0.0000006737 0.0000003017 1.8887411088<br /> &END COORD</div><div><br /></div><div>My geometry has been relaxed in a 6x6x2 supercell, with an RMS_FORCE setting of 1e-8 with the CELL_OPT method. The sum of atomic forces at the end lines up with this. I have converged my plane wave cutoff and relative plane wave cutoff (how converged does this need to be?). I worry it may be an issue with negative coordinates in the unit cell, however the periodic XYZ command should wrap these as I understand? </div><div><br /></div><div>If anyone has any suggestions as to why my phonons look quite bad I'd be very thankful.</div><div><br /></div><div>Thanks in advance </div><div>Ashley </div><div><br /></div>
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