<div dir="ltr"><div>Hi,</div><div><br></div>there is also the CENTER_GRID that has been introduced quite recently. I don't know how much it has been tested, maybe someone else can comment? But for my simple test water system it seems to improve the energy conservation considerably. The idea is, I think, to only center the QM molecule in a "quantized" manner on equivalent grid points of the (fine DFT?) grid.<div><br></div><div>To get really good energy conservation you might need to increase your cutoff/rel_cutoff too.<br><div><br></div><div>Matt<br><br>On Wednesday, March 18, 2015 at 11:22:10 AM UTC, Jonggu Jeon wrote:<blockquote class="gmail_quote" style="margin: 0;margin-left: 0.8ex;border-left: 1px #ccc solid;padding-left: 1ex;"><div dir="ltr">Dear Dorothea,<br><br>Thank you for the invaluable suggestion. <br>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.<br>Therefore, CP2K 2.5.1 produces the same (diverging) energy profile whether I set &MULTIPOLE OFF or not.<br><br>I will install version 2.6 and try it again.<br><br>Best regards,<br><br>Jonggu<br><br><br>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,<br><br></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<br>&MULTIPOLE OFF<br></div>&END<br><br></div>Also set in the QMMM section<br><br> &WALLS<br> TYPE NONE<br> &END WALLS<br><br></div>That should address your first question...<br><br></div>Cheers,<br></div>Dorothea<br><div><div><div><div><div> <br></div></div></div></div></div></div><div><br><div class="gmail_quote">2015-03-18 8:46 GMT+01:00 Jonggu Jeon <span dir="ltr"><<a rel="nofollow">jeon...@gmail.com</a>></span>:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Dear CP2K users,<br><br>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).<br><br>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).<br>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.<br><br>The following is the summary of my findings.<br><br>1. With FORCE_EVAL/QMMM/CENTER EVERY_STEP, the total energy is not conserved, as pointed out by Dr. Laino in this group before.<br>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:<br><br> *** 16:11:03 WARNING in qmmm_util:apply_qmmm_walls_<wbr>reflective :: One or ***<br> *** few QM atoms are within the SKIN of the quantum box. Check your run ***<br> *** and you may possibly consider: the activation of the QMMM WALLS ***<br> *** around the QM box, switching ON the centering of the QM box or ***<br> *** increase the size of the QM cell. CP2K CONTINUE but results could be ***<br> *** meaningless. qmmm_util.F line 206 <wbr> ***<br><br>My questions are as follows:<br><br>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.<br><br>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?<br><br>The skeletal form of my input file is attached below.<br>Thank you.<br><br>Jonggu Jeon<br><br><br><br> &MOTION<br> &MD<br> ENSEMBLE NVE<br> STEPS 40000<br> TIMESTEP 0.5<br> STEP_START_VAL 0<br> TIME_START_VAL 0<br> &END MD<br> &END MOTION<br> &FORCE_EVAL<br> METHOD QMMM<br> &DFT<br> BASIS_SET_FILE_NAME /opt/cp2k/2.5.1/tests/QS/GTH_<wbr>BASIS_SETS<br> POTENTIAL_FILE_NAME /opt/cp2k/2.5.1/tests/QS/<wbr>POTENTIAL<br> WFN_RESTART_FILE_NAME wfn.rst<br> CHARGE 0<br> &SCF<br> MAX_SCF 30<br> EPS_SCF 9.9999999999999995E-07<br> SCF_GUESS RESTART<br> &OT T<br> MINIMIZER DIIS<br> PRECONDITIONER FULL_ALL<br> ENERGY_GAP 1.0000000000000000E-03<br> &END OT<br> &OUTER_SCF T<br> EPS_SCF 9.9999999999999995E-07<br> MAX_SCF 1<br> &END OUTER_SCF<br> &END SCF<br> &QS<br> EPS_DEFAULT 1.0000000000000000E-10<br> MAP_CONSISTENT T<br> EXTRAPOLATION ASPC<br> EXTRAPOLATION_ORDER 3<br> METHOD GPW<br> &END QS<br> &MGRID<br> CUTOFF 2.8000000000000000E+02<br> COMMENSURATE T<br> &END MGRID<br> &XC<br> &XC_GRID<br> XC_SMOOTH_RHO NN50<br> XC_DERIV SPLINE2_SMOOTH<br> &END XC_GRID<br> &XC_FUNCTIONAL NO_SHORTCUT<br> &BECKE88 T<br> &END BECKE88<br> &LYP T<br> &END LYP<br> &END XC_FUNCTIONAL<br> &VDW_POTENTIAL<br> POTENTIAL_TYPE PAIR_POTENTIAL<br> &PAIR_POTENTIAL<br> TYPE DFTD3<br> PARAMETER_FILE_NAME /opt/cp2k/2.5.1/tests/QS/<wbr>dftd3.dat<br> REFERENCE_FUNCTIONAL BLYP<br> CALCULATE_C9_TERM F<br> REFERENCE_C9_TERM F<br> LONG_RANGE_CORRECTION F<br> &END PAIR_POTENTIAL<br> &END VDW_POTENTIAL<br> &END XC<br> &END DFT<br> &MM<br> &FORCEFIELD<br> PARMTYPE AMBER<br> PARM_FILE_NAME ndmd48.ao.prmtop<br> &SPLINE<br> EMAX_SPLINE 1.0000000000000000E+00<br> &END SPLINE<br> &END FORCEFIELD<br> &POISSON<br> &EWALD<br> EWALD_TYPE SPME<br> ALPHA 3.4999999999999998E-01<br> GMAX 18<br> &END EWALD<br> &END POISSON<br> &END MM<br> &QMMM<br> E_COUPL GAUSS<br> USE_GEEP_LIB 7<br> NOCOMPATIBILITY T<br> CENTER SETUP_ONLY<br> INITIAL_TRANSLATION_VECTOR -1.0888775605157457E+01 -2.9066675351256084E+00 7.3922596274008097E+00<br> &CELL<br> ABC 1.5084868700000001E+01 1.5084868700000001E+01 1.5084868700000001E+01<br> PERIODIC XYZ<br> &END CELL<br> &PERIODIC<br> GMAX 5.0000000000000000E-01<br> &MULTIPOLE<br> RCUT 1.2000000000000000E+01<br> EWALD_PRECISION 4.9999999999999998E-07<br> ANALYTICAL_GTERM T<br> NGRIDS 50 50 50<br> &END MULTIPOLE<br> &END PERIODIC<br> &END QMMM<br> &SUBSYS<br> &CELL<br> A 1.5084868700000001E+01 0.0000000000000000E+00 0.0000000000000000E+00<br> B 0.0000000000000000E+00 1.5084868700000001E+01 0.0000000000000000E+00<br> C 0.0000000000000000E+00 0.0000000000000000E+00 1.5084868700000001E+01<br> MULTIPLE_UNIT_CELL 1 1 1<br> &END CELL<br> &TOPOLOGY<br> NUMBER_OF_ATOMS 156<br> CONN_FILE_NAME ndmd48.ao.prmtop<br> CONN_FILE_FORMAT AMBER<br> MULTIPLE_UNIT_CELL 1 1 1<br> &END TOPOLOGY<br> &END SUBSYS<br> &END FORCE_EVAL<span><font color="#888888"><br><br></font></span></div><span><font color="#888888"> <p></p> -- <br> You received this message because you are subscribed to the Google Groups "cp2k" group.<br> To unsubscribe from this group and stop receiving emails from it, send an email to <a rel="nofollow">cp2k+...@googlegroups.com</a>.<br> To post to this group, send email to <a rel="nofollow">cp...@googlegroups.com</a>.<br> Visit this group at <a href="http://groups.google.com/group/cp2k" rel="nofollow" target="_blank" onmousedown="this.href='http://groups.google.com/group/cp2k';return true;" onclick="this.href='http://groups.google.com/group/cp2k';return true;">http://groups.google.com/<wbr>group/cp2k</a>.<br> For more options, visit <a href="https://groups.google.com/d/optout" rel="nofollow" target="_blank" onmousedown="this.href='https://groups.google.com/d/optout';return true;" onclick="this.href='https://groups.google.com/d/optout';return true;">https://groups.google.com/d/<wbr>optout</a>.<br> </font></span></blockquote></div><br></div> </blockquote></div></blockquote></div></div></div>