Many thanks for the clarifications, <span style="color: rgb(32, 33, 36); font-family: Roboto, Arial, sans-serif; letter-spacing: 0.25px; text-wrap-mode: nowrap;">Jürg Hutter! </span><div><span style="color: rgb(32, 33, 36); font-family: Roboto, Arial, sans-serif; letter-spacing: 0.25px; text-wrap-mode: nowrap;"><br /></span></div><div><span style="color: rgb(32, 33, 36); font-family: Roboto, Arial, sans-serif; letter-spacing: 0.25px; text-wrap-mode: nowrap;">Thanks for your time.</span><div><font color="#202124" face="Roboto, Arial, sans-serif"><span style="letter-spacing: 0.25px; text-wrap-mode: nowrap;"><br /></span></font></div><div><font color="#202124" face="Roboto, Arial, sans-serif"><span style="letter-spacing: 0.25px; text-wrap-mode: nowrap;">Best,</span></font></div><div><font color="#202124" face="Roboto, Arial, sans-serif"><span style="letter-spacing: 0.25px; text-wrap-mode: nowrap;"><br /></span></font></div><div><font color="#202124" face="Roboto, Arial, sans-serif"><span style="letter-spacing: 0.25px; text-wrap-mode: nowrap;">Emerson<br /></span></font><br /></div></div><div class="gmail_quote"><div dir="auto" class="gmail_attr">Em sexta-feira, 27 de junho de 2025 às 06:01:40 UTC-3, Jürg Hutter escreveu:<br/></div><blockquote class="gmail_quote" style="margin: 0 0 0 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">Hi
<br>
<br>CP2K does not use MIC for vdW corrections. You can specify any cutoff radius.
<br>Atoms within 2*R_CUTOFF will interact. You can check the convergence of the vdW
<br>energy by increasing the cutoff .
<br>
<br>regards
<br>JH
<br>
<br>________________________________________
<br>From: <a href data-email-masked rel="nofollow">cp...@googlegroups.com</a> <<a href data-email-masked rel="nofollow">cp...@googlegroups.com</a>> on behalf of emerson p l <<a href data-email-masked rel="nofollow">emers...@gmail.com</a>>
<br>Sent: Thursday, June 26, 2025 9:41 PM
<br>To: cp2k
<br>Subject: [CP2K:21590] Clarification of R_CUTOFF in VDW_POTENTIAL
<br>
<br>Dear cp2k community, I hope you’re all doing well.
<br>
<br>I’m writing to ask for clarification on the choice of the cutoff radius R_CUTOFF parameter when using periodic boundary conditions in VDW_POTENTIAL in AIMD and geometry/cell optimizations:
<br>
<br> &VDW_POTENTIAL
<br> POTENTIAL_TYPE PAIR_POTENTIAL
<br> &PAIR_POTENTIAL
<br> PARAMETER_FILE_NAME dftd3.dat
<br> TYPE DFTD3
<br> REFERENCE_FUNCTIONAL PBE
<br> R_CUTOFF [angstrom] 10
<br> &END
<br> &END VDW_POTENTIAL
<br>
<br>Suppose I have a cubic simulation box with side length L = 5 angstrom, and I (mistakenly) set R_CUTOFF = 10 angstrom. Would setting RCUTOFF = 10 angstrom in a 5 angstrom cubic box cause the cutoff sphere to extend beyond the primary cell and overlap with periodic images, resulting in unphysical, multiply-counted interactions?
<br>
<br>My understanding from classical MD is that we must obey the minimum-image convention, which requires R_CUTOFF ≤ 2 Lmin. I don't know if R_CUTOFF has this physical meaning of classical MD.
<br>
<br>Thank you very much for your time and insights.
<br>
<br>Best,
<br>
<br>Emerson
<br>
<br>
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