Thank you for your reply, it is very useful for me.<br><br><div class="gmail_quote"><div dir="auto" class="gmail_attr">在2022年10月16日星期日 UTC+8 00:18:30<Lucas Lodeiro> 写道：<br/></div><blockquote class="gmail_quote" style="margin: 0 0 0 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;"><div dir="ltr">Hello Mengchao,<div><br></div><div>AFAIK your results are consistent. Of course there are 24 normal modes, and 3 of them are translational ones. CP2K removes the translational modes before printing the data, you can find this in the CP2K output (search "VIB| Eigenvectors before removal" and " VIB| Frequencies after removal"), where the complete set of normal modes and frequencies are printed before the translational removal. This does not change significantly the results, so you can think about 21 normal modes and 3 extra translation modes with zero frequency.</div><div>In VASP the translational removal is not done and the low frequency modes are the translational ones... but at Gamma point they must be zero frequency. The resulting non zero value is an artifact of the PW rupture of translational invariance, which is due to the non complete PW basis set (infinite energy plane wave). As a guess, taking into account that in VASP the PW cutoff is lower compared with used in CP2K, and PW are used to wavefunctions, the error due to rupture of translational invariance is higher in VASP.</div><div><br></div><div>Regards - Lucas</div></div><br><div class="gmail_quote"></div><div class="gmail_quote"><div dir="ltr" class="gmail_attr">El vie, 14 oct 2022 a las 0:42, mengchao shi (<<a href data-email-masked rel="nofollow">smclu...@gmail.com</a>>) escribió:<br></div></div><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Dear all<div> I want to calculate the atomic frequency of diamond silicon by CP2K.<br> My supercell contains N=8 atoms (a PBC system), and I will get the 3N=24 frequencies.<br> </div><div> However, I only get the 21 frequencies, The frequencies of the rotations are obtained, but the part of translations are not obtained.</div><div><br></div><div> I use the VASP to calcualte the vibrational analysis, I get the 24 frequencies.</div><div> I compare the two results:</div><div> </div><div> VASP: (unit: cm-1, 24 frequencies ) </div> 513.100912 513.097046 513.092040 <br> 461.327377 461.230874 461.217489 461.210747 461.189027 461.185948<div> 409.422422 409.414429 409.406072 409.397086 409.393930 409.387741 </div><div> 140.194017 140.189188 140.187673 140.182783 140.175562 140.172242 </div><div><div> 0.006451 0.010431 0.055547 <br> </div><div> CP2K: (unit: cm-1, 21 frequencies) </div><div> 515.944308 515.944308 515.944308<div> 463.042397 463.042397 463.042397 463.042397 463.042397 463.042397<br></div><div> 412.993772 412.993772 412.993772 412.993772 412.993772 412.993772</div><div><div> 139.536054 139.536054 139.536054 139.536054 139.536054 139.536054</div><div> </div><div> The results are similar, but the number is different, how do I get 24 frequencies by CP2K. </div></div><div><br></div><div> The part input:</div><div> "</div><div> &GLOBAL</div> PROJECT system<br> RUN_TYPE VIBRATIONAL_ANALYSIS<br> PRINT_LEVEL MEDIUM<br> &END GLOBAL<br><br> &VIBRATIONAL_ANALYSIS<br> NPROC_REP 3<br> DX 0.001<br> FULLY_PERIODIC .TRUE.<br>&END VIBRATIONAL_ANALYSIS<br><div> "</div></div></div><div><br></div><div> Thank you for your help.</div><div> Best,</div><div> Mengchao.</div>
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