<html xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"> <head> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> <meta name="Generator" content="Microsoft Word 15 (filtered medium)"> <style></style> </head> <body lang="en-CH" link="blue" vlink="purple" style="word-wrap:break-word"> <div class="WordSection1"> That depends on your goals. I guess that you used a k point mesh with QE which you could apply likewise with CP2K to check if you get similar results. On the other hand, with k points less features are available and if you want to study larger unit cells (surface areas) later anyway then a supercell approach might be the better choice.<o:p></o:p> <o:p> </o:p> Matthias<o:p></o:p> <o:p> </o:p> <div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm"> From: cp2k@googlegroups.com <cp2k@googlegroups.com> on behalf of Diego López <diegolopal@gmail.com> Date: Wednesday, 24 May 2023 at 16:34 To: cp2k <cp2k@googlegroups.com> Subject: Re: [CP2K:18842] Unreal cell parameters obtained after CELL_OPT<o:p></o:p> </div> Thanks a lot for your suggestion Krack. Then, should I use k-points in the calculations or this MULTIPLE_UNIT_CELL option?<o:p></o:p> <div> <o:p> </o:p> </div> <div> Best,<o:p></o:p> </div> <div> Diego<o:p></o:p> </div> <div> <div> El miércoles, 24 de mayo de 2023 a las 15:39:06 UTC+2, Krack Matthias escribió:<o:p></o:p> </div> <blockquote style="border:none;border-left:solid #CCCCCC 1.0pt;padding:0cm 0cm 0cm 6.0pt;margin-left:4.8pt;margin-right:0cm"> <div> <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">MULTIPLE_UNIT_CELL</a> 3 3 1, i.e. a 3x3x1 supercell which has to be defined consistently in the &CELL and TOPOLOGY section.<o:p></o:p> </div> </div> <div> <div> <o:p></o:p> <div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm"> From: cp...@googlegroups.com <cp...@googlegroups.com> on behalf of Diego López <diego...@gmail.com> Date: Wednesday, 24 May 2023 at 14:08 To: cp2k <cp...@googlegroups.com> Subject: [CP2K:18839] Unreal cell parameters obtained after CELL_OPT<o:p></o:p> </div> Dear all,<o:p></o:p> <div> <o:p></o:p> </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.<o:p></o:p> </div> <div> <o:p></o:p> </div> <div> I used this input:<o:p></o:p> </div> <div> <o:p></o:p> </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">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<o:p></o:p> </div> <div> <o:p></o:p> </div> <div> <o:p></o:p> </div> </div> </div> <div> <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 cp2k+uns...@googlegroups.com. 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"> https://groups.google.com/d/msgid/cp2k/ffb8824d-4222-4ba7-8a85-f0a99c49ee46n%40googlegroups.com</a>.<o:p></o:p> </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>. 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