Thanks a lot for your suggestion Krack. Then, should I use k-points in the calculations or this MULTIPLE_UNIT_CELL option?<div> </div><div>Best,</div><div>Diego </div><div class="gmail_quote"><div dir="auto" class="gmail_attr">El miércoles, 24 de mayo de 2023 a las 15:39:06 UTC+2, Krack Matthias escribió: </div><blockquote class="gmail_quote" style="margin: 0 0 0 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;"> <div lang="en-CH" link="blue" vlink="purple" style="word-wrap:break-word"> <div> Without k points, I suggest to try <a href="https://manual.cp2k.org/cp2k-2023_1-branch/CP2K_INPUT/FORCE_EVAL/SUBSYS/CELL.html#MULTIPLE_UNIT_CELL" target="_blank" rel="nofollow" data-saferedirecturl="https://www.google.com/url?hl=es&q=https://manual.cp2k.org/cp2k-2023_1-branch/CP2K_INPUT/FORCE_EVAL/SUBSYS/CELL.html%23MULTIPLE_UNIT_CELL&source=gmail&ust=1685024950237000&usg=AOvVaw1H-1kaKKxV8gqOlAsOqYnC">MULTIPLE_UNIT_CELL</a> 3 3 1, i.e. a 3x3x1 supercell which has to be defined consistently in the &CELL and TOPOLOGY section.</div></div><div lang="en-CH" link="blue" vlink="purple" style="word-wrap:break-word"><div> <div style="border:none;border-top:solid #b5c4df 1.0pt;padding:3.0pt 0cm 0cm 0cm"> 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 Diego López <<a href data-email-masked rel="nofollow">diego...@gmail.com</a>> Date: Wednesday, 24 May 2023 at 14:08 To: cp2k <<a href data-email-masked rel="nofollow">cp...@googlegroups.com</a>> Subject: [CP2K:18839] Unreal cell parameters obtained after CELL_OPT </div> Dear all, <div> </div> <div> I have been trying to optimize a unit cell of the 2D semiconductor CrSBr using GPW method implemented in CP2K. The initial cell parameters were a = 3.6 A, b = 4.8 A and c = 25.0 A (obtained from previous calculations with Quantum Espresso and in good agreement with experimental data). After 128 optimization cycles the geometry is optimized and the obtained cell parameters were a = 3.64 A and b = 6.60 A, which leads to a meaningless structure since there is no longer a 2D structure. Also the geometry of the unit cell is really distorted. Any suggestions to improve the accuracy of my calculation? Thank you in advanced. </div> <div> </div> <div> I used this input: </div> <div> </div> <div> &GLOBAL PROJECT test2 RUN_TYPE CELL_OPT PRINT_LEVEL MEDIUM &END GLOBAL &FORCE_EVAL METHOD Quickstep ! Electronic structure method (DFT,...) STRESS_TENSOR ANALYTICAL &DFT BASIS_SET_FILE_NAME /BASIS_MOLOPT POTENTIAL_FILE_NAME /GTH_POTENTIALS MULTIPLICITY 7 &POISSON ! Solver requested for non periodic calculations PERIODIC XYZ &END POISSON &XC &XC_FUNCTIONAL PBE &END XC_FUNCTIONAL &END XC &SCF SCF_GUESS SPARSE MAX_SCF 100 &OT PRECONDITIONER FULL_KINETIC MINIMIZER CG &END OT &OUTER_SCF MAX_SCF 50 &END &END SCF &MGRID NGRIDS 4 CUTOFF 550 REL_CUTOFF 90 &END MGRID &QS METHOD GPW &END &END DFT &SUBSYS &CELL ABC 3.601367151 4.818258107 25.0 ALPHA_BETA_GAMMA 90 90 90 PERIODIC XYZ SYMMETRY ORTHORHOMBIC &END CELL &TOPOLOGY ! Section used to center the atomic coordinates in the given box. Useful for big molecules COORD_FILE_FORMAT xyz COORD_FILE_NAME ./<a href="http://crsbr.xyz" target="_blank" rel="nofollow" data-saferedirecturl="https://www.google.com/url?hl=es&q=http://crsbr.xyz&source=gmail&ust=1685024950237000&usg=AOvVaw3KgVMUrTqGmCf9Qgf9FFXr">crsbr.xyz</a> &END &KIND Cr ELEMENT Cr BASIS_SET DZVP-MOLOPT-SR-GTH POTENTIAL GTH-PBE-q14 MAGNETIZATION 3.0 &END KIND &KIND S ELEMENT S BASIS_SET TZV2P-MOLOPT-GTH POTENTIAL GTH-PBE-q6 &END KIND &KIND Br ELEMENT Br BASIS_SET DZVP-MOLOPT-SR-GTH POTENTIAL GTH-PBE-q7 &END KIND &END SUBSYS &END FORCE_EVAL &MOTION &CELL_OPT TYPE DIRECT_CELL_OPT MAX_DR 1.0E-03 MAX_FORCE 1.0E-03 RMS_DR 1.0E-03 RMS_FORCE 1.0E-03 MAX_ITER 200 OPTIMIZER BFGS KEEP_SYMMETRY &END CELL_OPT &GEO_OPT MAX_DR 1.0E-03 MAX_FORCE 1.0E-03 RMS_DR 1.0E-03 RMS_FORCE 1.0E-03 OPTIMIZER BFGS &END GEO_OPT &END MOTION </div> <div> </div> <div> </div> </div></div><div lang="en-CH" link="blue" vlink="purple" style="word-wrap:break-word"><div>-- You received this message because you are subscribed to the Google Groups "cp2k" group. To unsubscribe from this group and stop receiving emails from it, send an email to <a href data-email-masked rel="nofollow">cp2k+uns...@googlegroups.com</a>. To view this discussion on the web visit <a href="https://groups.google.com/d/msgid/cp2k/ffb8824d-4222-4ba7-8a85-f0a99c49ee46n%40googlegroups.com?utm_medium=email&utm_source=footer" target="_blank" rel="nofollow" data-saferedirecturl="https://www.google.com/url?hl=es&q=https://groups.google.com/d/msgid/cp2k/ffb8824d-4222-4ba7-8a85-f0a99c49ee46n%2540googlegroups.com?utm_medium%3Demail%26utm_source%3Dfooter&source=gmail&ust=1685024950237000&usg=AOvVaw2lm8vLZ_6tHVjQz0pPlu2r"> https://groups.google.com/d/msgid/cp2k/ffb8824d-4222-4ba7-8a85-f0a99c49ee46n%40googlegroups.com</a>. </div> </div> </blockquote></div> -- You received this message because you are subscribed to the Google Groups "cp2k" group. To unsubscribe from this group and stop receiving emails from it, send an email to <a href="mailto:cp2k+unsubscribe@googlegroups.com">cp2k+unsubscribe@googlegroups.com</a>. To view this discussion on the web visit <a href="https://groups.google.com/d/msgid/cp2k/ae820a14-e3e5-4be2-8dd6-5e60c6abc282n%40googlegroups.com?utm_medium=email&utm_source=footer">https://groups.google.com/d/msgid/cp2k/ae820a14-e3e5-4be2-8dd6-5e60c6abc282n%40googlegroups.com</a>.