<div dir="ltr">Dear Dorothea, Thank you for the invaluable suggestion. While your answer makes perfect sense to me, I just found out that CP2K 2.5.1 does not have option to turn off QMMM/PERIODIC/MULTIPOLE using the section parameter OFF. Therefore, CP2K 2.5.1 produces the same (diverging) energy profile whether I set &MULTIPOLE OFF or not. I will install version 2.6 and try it again. Best regards, Jonggu 2015년 3월 18일 수요일 오후 6시 22분 40초 UTC+9, Dorothea Golze 님의 말:<blockquote class="gmail_quote" style="margin: 0;margin-left: 0.8ex;border-left: 1px #ccc solid;padding-left: 1ex;"><div dir="ltr"><div><div><div><div><div><div>Hi, </div>if you have a fully periodic setup where the QM and MM boxes are equal, you do not need the decoupling/recoupling stuff, i.e. switch off explicitly the MULTIPOLE section like that &MULTIPOLE OFF </div>&END </div>Also set in the QMMM section &WALLS TYPE NONE &END WALLS </div>That should address your first question... </div>Cheers, </div>Dorothea <div><div><div><div><div> </div></div></div></div></div></div><div> <div class="gmail_quote">2015-03-18 8:46 GMT+01:00 Jonggu Jeon <<a href="javascript:" target="_blank" gdf-obfuscated-mailto="Z-miH6AKlU0J" rel="nofollow" onmousedown="this.href='javascript:';return true;" onclick="this.href='javascript:';return true;">jeon...@gmail.com</a>>: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Dear CP2K users, I'd like to ask some questions on the capabilities of the QM/MM part of CP2K (I'm using version 2.5.1, svn:13632). I've been attempting a QM/MM MD simulation with CP2K. My system consists of one NMA molecule (TZV2P/BLYP DFT) and 48 methanol molecules (OPLS MM force field). The relevant parts of my input file are attached at the end of the message. Basically, I'm following all the advices from this group for a fully periodic QM/MM setup and set the cell sizes for the QM (in QMMM/CELL) and MM (in SUBSYS/CELL) parts equal. The following is the summary of my findings. 1. With FORCE_EVAL/QMMM/CENTER EVERY_STEP, the total energy is not conserved, as pointed out by Dr. Laino in this group before. 2. With FORCE_EVAL/QMMM/CENTER SETUP_ONLY, the total energy is very well conserved within 0.1 kcal/mol for a few ps until the QM molecule eventually crosses the cell boundary. At this point system energy shoots up by several kcal/mol and the output begins to produce the following messages: *** 16:11:03 WARNING in qmmm_util:apply_qmmm_walls_reflective :: One or *** *** few QM atoms are within the SKIN of the quantum box. Check your run *** *** and you may possibly consider: the activation of the QMMM WALLS *** *** around the QM box, switching ON the centering of the QM box or *** *** increase the size of the QM cell. CP2K CONTINUE but results could be *** *** meaningless. qmmm_util.F line 206 *** My questions are as follows: 1. Is it possible to achieve the energy conservation in a fully periodic DFT/MM MD without worrying about the QM molecule crossing the cell boundary? I believe this is possible in full DFT MD but my experience on CP2K QM/MM so far indicates otherwise. I'd appreciate if someone can provide an answer and keywords to achieve it. 2. The QMMM/CENTER option affects energy conservation a lot. When CENTER EVERY_STEP is used, would it improve energy conservation if I use finer grids by increasing DFT/MGRID/CUTOFF value? The skeletal form of my input file is attached below. Thank you. Jonggu Jeon &MOTION &MD ENSEMBLE NVE STEPS 40000 TIMESTEP 0.5 STEP_START_VAL 0 TIME_START_VAL 0 &END MD &END MOTION &FORCE_EVAL METHOD QMMM &DFT BASIS_SET_FILE_NAME /opt/cp2k/2.5.1/tests/QS/GTH_BASIS_SETS POTENTIAL_FILE_NAME /opt/cp2k/2.5.1/tests/QS/POTENTIAL WFN_RESTART_FILE_NAME wfn.rst CHARGE 0 &SCF MAX_SCF 30 EPS_SCF 9.9999999999999995E-07 SCF_GUESS RESTART &OT T MINIMIZER DIIS PRECONDITIONER FULL_ALL ENERGY_GAP 1.0000000000000000E-03 &END OT &OUTER_SCF T EPS_SCF 9.9999999999999995E-07 MAX_SCF 1 &END OUTER_SCF &END SCF &QS EPS_DEFAULT 1.0000000000000000E-10 MAP_CONSISTENT T EXTRAPOLATION ASPC EXTRAPOLATION_ORDER 3 METHOD GPW &END QS &MGRID CUTOFF 2.8000000000000000E+02 COMMENSURATE T &END MGRID &XC &XC_GRID XC_SMOOTH_RHO NN50 XC_DERIV SPLINE2_SMOOTH &END XC_GRID &XC_FUNCTIONAL NO_SHORTCUT &BECKE88 T &END BECKE88 &LYP T &END LYP &END XC_FUNCTIONAL &VDW_POTENTIAL POTENTIAL_TYPE PAIR_POTENTIAL &PAIR_POTENTIAL TYPE DFTD3 PARAMETER_FILE_NAME /opt/cp2k/2.5.1/tests/QS/dftd3.dat REFERENCE_FUNCTIONAL BLYP CALCULATE_C9_TERM F REFERENCE_C9_TERM F LONG_RANGE_CORRECTION F &END PAIR_POTENTIAL &END VDW_POTENTIAL &END XC &END DFT &MM &FORCEFIELD PARMTYPE AMBER PARM_FILE_NAME ndmd48.ao.prmtop &SPLINE EMAX_SPLINE 1.0000000000000000E+00 &END SPLINE &END FORCEFIELD &POISSON &EWALD EWALD_TYPE SPME ALPHA 3.4999999999999998E-01 GMAX 18 &END EWALD &END POISSON &END MM &QMMM E_COUPL GAUSS USE_GEEP_LIB 7 NOCOMPATIBILITY T CENTER SETUP_ONLY INITIAL_TRANSLATION_VECTOR -1.0888775605157457E+01 -2.9066675351256084E+00 7.3922596274008097E+00 &CELL ABC 1.5084868700000001E+01 1.5084868700000001E+01 1.5084868700000001E+01 PERIODIC XYZ &END CELL &PERIODIC GMAX 5.0000000000000000E-01 &MULTIPOLE RCUT 1.2000000000000000E+01 EWALD_PRECISION 4.9999999999999998E-07 ANALYTICAL_GTERM T NGRIDS 50 50 50 &END MULTIPOLE &END PERIODIC &END QMMM &SUBSYS &CELL A 1.5084868700000001E+01 0.0000000000000000E+00 0.0000000000000000E+00 B 0.0000000000000000E+00 1.5084868700000001E+01 0.0000000000000000E+00 C 0.0000000000000000E+00 0.0000000000000000E+00 1.5084868700000001E+01 MULTIPLE_UNIT_CELL 1 1 1 &END CELL &TOPOLOGY NUMBER_OF_ATOMS 156 CONN_FILE_NAME ndmd48.ao.prmtop CONN_FILE_FORMAT AMBER MULTIPLE_UNIT_CELL 1 1 1 &END TOPOLOGY &END SUBSYS &END FORCE_EVAL </div> -- You received this message because you are subscribed to the Google Groups "cp2k" group. 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