<div dir="ltr">Dear CP2K users,<div>I'm wondering if I implemented RPBE right or not. I compared the inter-molecular interaction of water dimers using B97M_rV and RPBE functionals. But I found that the binding energy difference is quiet large. The energy based on B97M_rV is 5.19 kcal/mol, while RPBE is only 1.65 kcal/mol. I'm sure the B97M_rV result is correct. So why RPBE underestimate the energy quite large. I attach the input for RPBE (one water) here, please help me check it. Thanks in advance!</div><div>Best regards,</div><div>Wanlu</div><div><br></div><div>&FORCE_EVAL<br>        METHOD QS<br>        &DFT<br>                BASIS_SET_FILE_NAME BASIS_MOLOPT<br>                POTENTIAL_FILE_NAME GTH_POTENTIALS<br>                &MGRID<br>                        CUTOFF 1200<br>                        REL_CUTOFF 60<br>                &END MGRID<br>                &QS<br>                        EPS_DEFAULT 1.0E-12<br>                &END QS<br>                &SCF<br>                   EPS_SCF 1.0E-6 <br></div><div>                   &OT ON<br>                           MINIMIZER DIIS<br>                   &END OT<br>                   &OUTER_SCF ON  <br>                           MAX_SCF 5<br>                           EPS_SCF 1.0E-6<br></div><div>                   &END OUTER_SCF<br>                  &END SCF<br>                  &XC<br>                        &XC_FUNCTIONAL<br>                                &LIBXC<br>                                        FUNCTIONAL GGA_X_RPBE<br>                                &END LIBXC<br></div><div>                        &END XC_FUNCTIONAL<br></div><div>                        &XC_GRID<br>                                XC_DERIV NN50_SMOOTH<br>                        &END XC_GRID<br>                 &END XC<br>                 &POISSON<br>                         PERIODIC none<br>                         POISSON_SOLVER wavelet<br>                 &END POISSON<br>        &END DFT<br>        &SUBSYS<br>                &CELL<br>                        ABC 20.0 20.0 20.0<br>                        ALPHA_BETA_GAMMA 90.0 90.0 90.0<br>                        PERIODIC NONE<br>                &END CELL<br>                &COORD<br></div><div>                O   1.350625   0.111469   0.000000<br>                H   1.680398  -0.373741  -0.758561<br>                H   1.680398  -0.373741   0.758561<br>                &END COORD<br>                &TOPOLOGY<br>                        &CENTER_COORDINATES<br>                        &END CENTER_COORDINATES<br>                &END TOPOLOGY<br>                &KIND O<br>                        BASIS_SET TZVP-MOLOPT-GTH<br>                        POTENTIAL GTH-PBE-q6<br>                &END KIND<br>                 &KIND H<br>                         BASIS_SET TZVP-MOLOPT-GTH<br>                         POTENTIAL GTH-PBE-q1<br>                &END KIND<br><br>         &END SUBSYS<br>&END FORCE_EVAL<br><br>&GLOBAL<br>        PROJECT Dimer_SP<br>        RUN_TYPE Energy<br>&END GLOBAL<br></div></div>