<div dir="ltr"><div>Dear Fabian</div><div><br></div><div>
<div>I am interested in studying the structural, electronic, and optical properties of periodic systems. I 
used to calculate the gas phase using Gaussian software. Now for the first time, I want to calculate in solid-state by cp2k. I have got some basic questions about periodic calculations. Please forgive me if I am asking very general questions, and so many....!<br></div><div><br></div><div>I want to start from the crystal X-ray structure...you can see it in the attached file!</div><div><br></div><div>1)
 Can I replace some of its atoms with arbitrary atoms? for example F 
atom instead of H atom... If I can, I must do calculations by cell-opt 
run type??? or geo-opt is also good?! 

</div><div><br></div><div> 2) As you see in the attached file, in my x-ray unit cell, there are some atoms outside of the box. 
<span lang="en"><span><span>Should such atoms be deleted before converting the CIF file to XYZ format? or not?</span></span></span></div><div><span lang="en"><span><span><br></span></span></span></div><div><span lang="en"><span><span>3)
<span lang="en"><span><span>Can this structure be investigated in 2D?<br></span></span></span></span></span></span></div><div><span lang="en"><span><span><br></span></span></span></div><div><span lang="en"><span><span>4)
<span lang="en"><span><span>If I want to investigate the electronic and 
optical properties of this structure, can I use the single unit 
cell or should it be in the form of a supercell? Are the properties of 
the unit cell and supercell different?</span></span></span></span></span></span></div><div><span lang="en"><span><span><span lang="en"><span><span><br></span></span></span></span></span></span></div><div><span lang="en"><span><span><span lang="en"><span><span>5) 
<span lang="en"><span><span>There is an important physical concept in the solid-state called k point!
<span lang="en"><span><span>Is it necessary to enter its keyword ?! or it is set by default...I don't know? 
<span lang="en"><span><span>Do you think I should enter it in the input file?</span></span></span> whether unit-cell or supercell!</span></span></span></span></span></span></span></span></span></span></span></span></div><div><span lang="en"><span><span><span lang="en"><span><span><span lang="en"><span><span><span lang="en"><span><span>   <br></span></span></span></span></span></span></span></span></span></span></span></span></div><div><span lang="en"><span><span><span lang="en"><span><span><span lang="en"><span><span><span lang="en"><span><span><br></span></span></span></span></span></span></span></span></span></span></span></span></div><div><span lang="en"><span><span><span lang="en"><span><span><span lang="en"><span><span><span lang="en"><span><span>
<span> <span><span>I am very sincerely eager to get an answer?</span></span> <span><span>please.</span></span></span> <br></span></span></span></span></span></span></span></span></span></span></span></span></div><div><span lang="en"><span><span><span lang="en"><span><span><span lang="en"><span><span><span lang="en"><span><span><br></span></span></span></span></span></span></span></span></span></span></span></span></div><div><span lang="en"><span><span><span lang="en"><span><span><span lang="en"><span><span><span lang="en"><span><span>Thanks a lot for helping</span></span></span></span></span></span></span></span></span></span></span></span></div>

</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Jun 29, 2021 at 12:05 AM Tahere Kheshti <<a href="mailto:tahere...@gmail.com" target="_blank">tahere...@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div>Dear Thomas <br></div><div><br></div><div>
<span lang="en"><span><span>Thanks for your helping!</span></span><span><span>
</span></span><span><span>I am a new user and I do not know some points.</span></span><span><span><br></span></span></span></div><div><span lang="en"><span><span><br></span></span></span></div><div><span lang="en"><span><span>
</span></span><span><span>Do you mean to use the default value for the number of optimization steps?</span></span><span><span>
</span></span><span><span><br></span></span></span></div><div><span lang="en"><span><span>Yes, unfortunately in the convergence of SCF, DIIS switched to SD, you suggested that I reduce the size.</span></span> <span><span>What value is good?</span></span></span> 

</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Jun 28, 2021 at 11:57 PM <a href="mailto:fa...@gmail.com" target="_blank">fa...@gmail.com</a> <<a href="mailto:fabia...@gmail.com" target="_blank">fabia...@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div>Hi</div><div><br></div><div>Your initial guess seems to be pretty bad: The structure at step 0 has a pressure of 5'546'592 bar and the first BFGS iteration reduces the energy by more than 50 Hartree, which is enormous. The volume of your cell increases by a factor of 2 over the 30 BFGS iterations. Maybe you could try to improve the initial configuration. This would certainly help the convergence of the SCF and BFGS.</div><div><br></div><div>Cheers Fabian<br></div><div class="gmail_quote"><div dir="auto" class="gmail_attr">On Monday, 28 June 2021 at 20:50:52 UTC+2 tkuehne wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div>Dear Tahere, <div><br></div><div>your geometry optimization is far from being converged. Instead of limiting the number </div><div>of optimization steps to 30, better simply rely on the convergence criteria. </div><div>SCF convergence, however, is much better when OT switches into the SD fallback mode </div><div>is always bad news. Try to reduce the OT stepsize …</div><div><br></div><div>Best, </div><div>Thomas<br><div><br><blockquote type="cite"></blockquote></div></div></div><div><div><div><blockquote type="cite"><div>Am 28.06.2021 um 17:39 schrieb Tahere Kheshti <<a rel="nofollow">tah...@gmail.com</a>>:</div><br></blockquote></div></div></div><div><div><div><blockquote type="cite"><div><div dir="ltr"><div>Hello everyone</div><div>I am attaching the input and output files. As you see 
none of the criteria for optimized geometry
has been reached.


<span lang="en"><span><span>Do I need to increase the number of optimization steps?</span></span></span> how many is enough? (my structure has 114 atoms)</div><div><span lang="en"><span><span>Are the number of inner and outer SCF steps appropriate?</span></span></span></div><div><span lang="en"><span><span><br></span></span></span></div><div><span lang="en"><span><span>
<span lang="en"><span><span>Can you please tell me your suggestions?</span></span></span></span></span></span></div><div><span lang="en"><span><span><span lang="en"><span><span>Thanks<br></span></span></span>

</span></span></span></div><div><span lang="en"><span><span> <br></span></span></span>

</div></div><div><br></div></div></blockquote></div></div></div><div><div><div><blockquote type="cite"><div>

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