<div dir="ltr">Hi Juerg, <div> </div><div>Thanks very much. I tried without dispersion correction for DZVP basis set, CUTOFF 500 and REL_CUTOFF 80. I got better results( B = 90 GPa).</div><div>I didn't understand how I can find my calculation is converged or not?</div> <div>For k-points you mean the system of 64 atoms is not big enough and I have to check with small unit cell (8 atoms) and then with MULTIPLE_UNIT_CELL keyword increase the size of the system and to see how it is converged?</div> <div> </div><div>Regards, </div><div>Leila</div><div> </div></div><div class="gmail_extra"> <div class="gmail_quote">On Mon, Aug 12, 2013 at 3:17 PM, <<a href="mailto:hut...@pci.uzh.ch" target="_blank">hut...@pci.uzh.ch</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi I would guess that your calculation is not yet converged with respect to 1) the basis set 2) the k-points. I would use a small unit cell and then the MULTIPLE_UNIT_CELL keyword to check for convergence 3) the cutoff, you are probably close here (REL_CUTOFF 80, just to be sure) I would still use the REF_CELL keyword in order to do constant number of grid point calculations 4) the dispersion correction will change the reference PBE value <div class="im"> regards Juerg -------------------------------------------------------------- Juerg Hutter Phone : <a href="tel:%2B%2B41%2044%20635%204491" value="+41446354491">++41 44 635 4491</a> Physical Chemistry Institute FAX : <a href="tel:%2B%2B41%2044%20635%206838" value="+41446356838">++41 44 635 6838</a> University of Zurich E-mail: <a href="mailto:hut...@pci.uzh.ch">hut...@pci.uzh.ch</a> Winterthurerstrasse 190 CH-8057 Zurich, Switzerland --------------------------------------------------------------- -----<a href="mailto:cp...@googlegroups.com">cp...@googlegroups.com</a> wrote: ----- To: <a href="mailto:cp...@googlegroups.com">cp...@googlegroups.com</a> </div>From: leila salimi Sent by: <a href="mailto:cp...@googlegroups.com">cp...@googlegroups.com</a> Date: 08/12/2013 03:05PM Subject: Re: [CP2K:4550] Bulk modulus of silicon with CP2K <div class="HOEnZb"><div class="h5"> Dear Juerg, Thanks for your answer. 1) the PBE value for B is 89 GPa. 2) I also tried with higher cutoff and REF_CUTOFF, but it didn't change. &MGRID NGRIDS 8 CUTOFF 500 REL_CUTOFF 60 &END MGRID On Mon, Aug 12, 2013 at 2:40 PM, <<a href="mailto:hut...@pci.uzh.ch">hut...@pci.uzh.ch</a>> wrote: Hi two things to do: 1) What is the official PBE value for this quantity? 2) Use a REF_CELL and a high enough cutoff (has to be tested) in order to get a smooth enough pressure curve regards Juerg -------------------------------------------------------------- Juerg Hutter Phone : <a href="tel:%2B%2B41%2044%20635%204491" value="+41446354491">++41 44 635 4491</a> Physical Chemistry Institute FAX : <a href="tel:%2B%2B41%2044%20635%206838" value="+41446356838">++41 44 635 6838</a> University of Zurich E-mail: <a href="mailto:hut...@pci.uzh.ch">hut...@pci.uzh.ch</a> Winterthurerstrasse 190 CH-8057 Zurich, Switzerland --------------------------------------------------------------- -----<a href="mailto:cp...@googlegroups.com">cp...@googlegroups.com</a> wrote: ----- To: <a href="mailto:cp...@googlegroups.com">cp...@googlegroups.com</a> From: leila Sent by: <a href="mailto:cp...@googlegroups.com">cp...@googlegroups.com</a> Date: 08/12/2013 11:57AM Subject: [CP2K:4549] Bulk modulus of silicon with CP2K Hi all, I simulated the silicon with 64 atoms and calculated the energy-volume plot and fitted with murnaghan. I found the lattice parameter 5.48 A ( lattice parameter in experiment is 5.44 A), That is OK but the bulk modulus is 63 GPa that is very low. (B_exp = 100 GPa) I really don' t know why cp2k gets B so low??? I tried with DZVP basis set and PBE functional with 280 Ryd cut off for density. I also checked with TZVP, it is not changing so much. It is 66 GPa. Can anybody help me with that? You can find my inputfile in below. &GLOBAL PROJECT si64-10.88A PRINT_LEVEL LOW RUN_TYPE GEO_OPT &END GLOBAL &MOTION &CELL_OPT TYPE GEO_OPT OPTIMIZER CG MAX_ITER 20 EXTERNAL_PRESSURE [bar] 1.0 MAX_DR 0.02 RMS_DR 0.01 MAX_FORCE 0.0002 RMS_FORCE 0.0001 KEEP_ANGLES &CG &LINE_SEARCH TYPE 2PNT &2PNT &END &END &END &END &GEO_OPT MAX_ITER 200 MINIMIZER BFGS &END &PRINT &STRESS &END STRESS &RESTART &EACH CELL_OPT 1 &END &END &END &END &FORCE_EVAL METHOD QS STRESS_TENSOR ANALYTICAL &DFT BASIS_SET_FILE_NAME ./BASIS_MOLOPT POTENTIAL_FILE_NAME ./GTH_POTENTIALS &MGRID CUTOFF 280 &END MGRID &QS METHOD GPW &END QS &SCF SCF_GUESS RESTART MAX_SCF 20 EPS_SCF 1.0e-5 &OUTER_SCF EPS_SCF 1.0E-5 &END &OT ON # MINIMIZER DIIS ROTATION &END OT &PRINT &RESTART BACKUP_COPIES 0 &END RESTART &END PRINT &END SCF &XC &XC_FUNCTIONAL PBE &END XC_FUNCTIONAL &vdW_POTENTIAL DISPERSION_FUNCTIONAL PAIR_POTENTIAL &PAIR_POTENTIAL TYPE DFTD3 CALCULATE_C9_TERM .TRUE. REFERENCE_C9_TERM .TRUE. LONG_RANGE_CORRECTION .TRUE. PARAMETER_FILE_NAME ./dftd3.dat REFERENCE_FUNCTIONAL PBE R_CUTOFF 8. EPS_CN 0.01 &END PAIR_POTENTIAL &END vdW_POTENTIAL &END XC &END DFT &SUBSYS &TOPOLOGY COORD_FILE_NAME ./GEOMETRY.xyz COORDINATE XYZ # CONNECTIVITY OFF &END TOPOLOGY &KIND Si BASIS_SET DZVP-MOLOPT-SR-GTH # BASIS_SET SZV-MOLOPT-SR-GTH # BASIS_SET TZVP-MOLOPT-GTH POTENTIAL GTH-PBE-q4 &END &CELL ABC 10.88 10.88 10.88 &END &END SUBSYS &END -- 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%2Bun...@googlegroups.com">cp2k+uns...@googlegroups.com</a>. To post to this group, send email to <a href="mailto:cp...@googlegroups.com">cp...@googlegroups.com</a>. Visit this group at <a href="http://groups.google.com/group/cp2k" target="_blank">http://groups.google.com/group/cp2k</a>. 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Visit this group at <a href="http://groups.google.com/group/cp2k" target="_blank">http://groups.google.com/group/cp2k</a>. For more options, visit <a href="https://groups.google.com/groups/opt_out" target="_blank">https://groups.google.com/groups/opt_out</a>. </div></div></blockquote></div> </div>