<div dir="ltr"><div style="text-align: left;">Dear CP2K experts,</div><div><br></div><div>I have a very rudimental (probably stupid) question.....</div><div><br></div><div>Energy of face centered cubic Si which calculated by VASP <br>found at VASPwiki example page (<a href="https://cms.mpi.univie.ac.at/wiki/index.php/Fcc_Si">https://cms.mpi.univie.ac.at/wiki/index.php/Fcc_Si</a>)<br>is -4.8758538 eV when the lattice parameter is 3.9 angstrom.</div><div><br></div><div>I also found fcc Si calculations at the CP2K tutorial pages.<br> ( "Simple Static Energy and Force Calculation Using QUICKSTEP"(<a href="http://www.cp2k.org/tutorials:static_calculation">http://www.cp2k.org/tutorials:static_calculation</a>)<br>and "How To Converge The Multi-Grid Used in QUICKSTEP"(<a href="http://www.cp2k.org/tutorials:converging_grid">http://www.cp2k.org/tutorials:converging_grid</a>) )</div><div><br></div><div>Energy cutoff values, lattice parameters and XC functional are different between these VASP and CP2K cases,<br>and SCF_MAX is set to 1 in the case of CP2K.<br>So I calculated fcc Si energy with CP2K 5.1 setting the energy cutoff 240 eV ~ 8.820 a.u., the lattice parameter 3.9 angstrom,<br> XC functional PBE and SCF_MAX defaut value.</div><div><br></div><p>The input file is the following:<br>-----------------------------------------------------------------<br>@SET twice_lp 7.80</p><p>&GLOBAL<br> PROJECT Si_bulk8<br> RUN_TYPE ENERGY<br> PRINT_LEVEL MEDIUM<br>&END GLOBAL<br>&FORCE_EVAL<br> METHOD Quickstep<br> &DFT<br> BASIS_SET_FILE_NAME BASIS_SET<br> POTENTIAL_FILE_NAME GTH_POTENTIALS<br> &MGRID<br> CUTOFF 8.820<br> &END MGRID<br> &QS<br> EPS_DEFAULT 1.0E-10<br> &END QS<br> &SCF<br> SCF_GUESS ATOMIC<br> EPS_SCF 1.0E-6<br> ADDED_MOS 10<br> CHOLESKY INVERSE<br> &SMEAR ON<br> METHOD FERMI_DIRAC<br> ELECTRONIC_TEMPERATURE [K] 300<br> &END SMEAR<br> &DIAGONALIZATION<br> ALGORITHM STANDARD<br> &END DIAGONALIZATION<br> &MIXING<br> METHOD BROYDEN_MIXING<br> ALPHA 0.4<br> BETA 0.5<br> NBROYDEN 8<br> &END MIXING<br> &END SCF<br> &XC<br> &XC_FUNCTIONAL PBE<br> &END XC_FUNCTIONAL<br> &END XC<br> &END DFT<br> &SUBSYS<br> &KIND Si<br> ELEMENT Si<br> BASIS_SET DZVP-GTH-PBE<br> POTENTIAL GTH-PBE-q4<br> &END KIND<br> &CELL<br> SYMMETRY CUBIC<br> A ${twice_lp} 0.00 0.00<br> B 0.00 ${twice_lp} 0.00<br> C 0.00 0.00 ${twice_lp}<br> &END CELL<br> &COORD<br> SCALED<br> Si 0.00 0.00 0.00<br> Si 0.00 0.50 0.50<br> Si 0.50 0.50 0.00<br> Si 0.50 0.00 0.50<br> Si 0.75 0.25 0.75<br> Si 0.25 0.25 0.25 <br> Si 0.25 0.75 0.75<br> Si 0.75 0.75 0.25<br> &END COORD<br> &END SUBSYS<br> &PRINT<br> &TOTAL_NUMBERS ON<br> &END TOTAL_NUMBERS<br> &END PRINT<br>&END FORCE_EVAL</p><div>-----------------------------------------------------------------</div><div><br></div><p>A part of the result by CP2K 5.1 is<br>-----------------------------------------------------------------<br>SCF WAVEFUNCTION OPTIMIZATION</p><p> Step Update method Time Convergence Total energy Change<br> ------------------------------------------------------------------------------<br> 1 NoMix/Diag. 0.40E+00 0.2 3.06132393 -28.5675142867 -2.86E+01<br> 2 Broy./Diag. 0.40E+00 0.3 2.32214549 -28.7998050659 -2.32E-01<br> 3 Broy./Diag. 0.40E+00 0.3 0.58522732 -29.4698863750 -6.70E-01<br> 4 Broy./Diag. 0.40E+00 0.3 0.20998859 -29.2828168394 1.87E-01<br> 5 Broy./Diag. 0.40E+00 0.3 0.12057075 -29.1932153866 8.96E-02<br> 6 Broy./Diag. 0.40E+00 0.3 0.05618396 -29.1361561613 5.71E-02<br> 7 Broy./Diag. 0.40E+00 0.3 0.01016729 -29.1363881842 -2.32E-04<br> 8 Broy./Diag. 0.40E+00 0.3 0.00251115 -29.1338276656 2.56E-03<br> 9 Broy./Diag. 0.40E+00 0.3 0.00053053 -29.1364584302 -2.63E-03<br> 10 Broy./Diag. 0.40E+00 0.3 0.00012439 -29.1370164369 -5.58E-04<br> 11 Broy./Diag. 0.40E+00 0.3 0.00008751 -29.1372252303 -2.09E-04<br> 12 Broy./Diag. 0.40E+00 0.3 0.00001301 -29.1371970535 2.82E-05<br> 13 Broy./Diag. 0.40E+00 0.3 0.00001000 -29.1371543754 4.27E-05<br> 14 Broy./Diag. 0.40E+00 0.3 0.00000033 -29.1371468686 7.51E-06</p><div> *** SCF run converged in 14 steps ***</div><div><br></div><p> Electronic density on regular grids: -32.0116716966 -0.0116716966<br> Core density on regular grids: 32.0008931651 0.0008931651<br> Total charge density on r-space grids: -0.0107785315<br> Total charge density g-space grids: -0.0107785315</p><p> Overlap energy of the core charge distribution: 0.00000000000000<br> Self energy of the core charge distribution: -82.06393942512820<br> Core Hamiltonian energy: 15.15717724613789<br> Hartree energy: 46.02547467061829<br> Exchange-correlation energy: -8.25223104355429<br> Electronic entropic energy: -0.00362831666283<br> Fermi energy: -0.03620657710631</p><p> Total energy: -29.13714686858875</p><div>-----------------------------------------------------------------</div><div><br></div><div>The obtained energy per atom is -29.13714686858875 / 8 = -3.64214335857359375 a.u. ~ -99.10776 eV<br>This is very different from -4.8758538 eV.</div><div><br></div><div>Could anyone interpret the difference between these results?<br>Thank you in advance.</div><div><br></div><div>brhr <br></div></div>