Hi Dune <br /><br />The origin of the increase of the SCF cycle in principle is because the calculation still trying to find the best wave functions, this is why if you look at your output (grep time out.out) the first step of SCF convergence always takes longer than the later. Since you start from the restart file, assume that you have the wfn file (i.e., file-RESTART.wfn) then you can use it to decrease the SCF cycle and speed up the calculation with the following<br />-------------------------------------------------------------------<br />&SCF<br /> ....<br /> SCF_GUESS HISTORY_RESTART<br /> ....<br />&END SCF <br />-------------------------------------------------------------------<br /><br />Hope it help <br /><br />Best<br />Saleh<br /><br /><br /><div class="gmail_quote"><div dir="auto" class="gmail_attr">On Monday, June 5, 2023 at 7:09:38 PM UTC+2 Dune André wrote:<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 style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">Dear all,<br></div><div style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)"><br></div><div style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">I
am facing an issue while running AIMD simulations of a box of ~1000
atoms. The system is an amorphous MOF made of Fe linked by benzene
tricarboxylate (named Fe-BTC).</div><div style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)"><br></div><div style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">I
use PBE functional with DZVP basis set and GTH pseudopotential ; DIIS
method and FULL_KINETIC preconditioner. I perform the calculation from a
restart file. The first steps of the MD are quite fast with ~10 SCF
steps per MD step. But along the AIMD run, the SCF cycles become longer
and longer (~100 SCF steps per MD step). <br></div><div style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)"><br></div><div style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">I
tried to use other OT method such as CG or other preconditioner such as
FULL_SINGLE_INVERSE but in both cases the SCF cycles are taking too
much time and sometimes fail to converge. Besides, FULL_ALL
preconditioner is too computationally expensive in terms of memory.<br></div><div style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)"><br></div><div style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">Do you have some ideas of the origin of this increase of the SCF cycles? I attached the restart file to the message. <br></div><div style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)"><br></div><div style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">Thanks in advance for your help,</div><div style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)"><br></div><div style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">Kind regards,</div><div style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)"><br></div><div style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">Dune André<br></div></blockquote></div>
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