Hi all,<div><br></div><div>I am very new to DFT calculations, let alone CP2k, so some level of idiocy on my part should be expected.</div><div>As a simple test, I am trying to calculate the binding energy of a Ni atom in a bulk crystal. The relevant portion of the input shown below:</div><div><br></div><div>***</div><div><div><font face="courier new, monospace" size="2">&GLOBAL</font></div><div><font face="courier new, monospace" size="2"> PROJECT Ni_inp_test</font></div><div><font face="courier new, monospace" size="2"> RUN_TYPE ENERGY_FORCE</font></div><div><font face="courier new, monospace" size="2"> PRINT_LEVEL LOW</font></div><div><font face="courier new, monospace" size="2">&END GLOBAL</font></div><div><font face="courier new, monospace" size="2">&FORCE_EVAL</font></div><div><font face="courier new, monospace" size="2"> METHOD Quickstep</font></div><div><font face="courier new, monospace" size="2"> &SUBSYS</font></div><div><font face="courier new, monospace" size="2"> &KIND Ni</font></div><div><font face="courier new, monospace" size="2"> ELEMENT<span class="Apple-tab-span" style="white-space:pre"> </span>Ni</font></div><div><font face="courier new, monospace" size="2"> BASIS_SET DZV-GTH-PADE-q18</font></div><div><font face="courier new, monospace" size="2"> POTENTIAL GTH-PADE-q10</font></div><div><font face="courier new, monospace" size="2"> &END KIND</font></div><div><font face="courier new, monospace" size="2"> &CELL</font></div><div><font face="courier new, monospace" size="2"> A 1.765000 1.765000 0.000000</font></div><div><font face="courier new, monospace" size="2"> B 0.000000 1.765000 1.765000</font></div><div><font face="courier new, monospace" size="2"> C<span class="Apple-tab-span" style="white-space:pre"> </span> 1.765000 0.000000 1.765000</font></div><div><font face="courier new, monospace" size="2"> PERIODIC<span class="Apple-tab-span" style="white-space:pre"> </span>XYZ</font></div><div><font face="courier new, monospace" size="2"> &END CELL</font></div><div><font face="courier new, monospace" size="2"> &COORD</font></div><div><font face="courier new, monospace" size="2"> Ni 0.000000000 0.000000000 0.000000000</font></div><div><font face="courier new, monospace" size="2"> &END COORD</font></div><div><font face="courier new, monospace" size="2"> &END SUBSYS</font></div><div><font face="courier new, monospace" size="2"> &DFT</font></div><div><font face="courier new, monospace" size="2"> BASIS_SET_FILE_NAME BASIS_SET</font></div><div><font face="courier new, monospace" size="2"> POTENTIAL_FILE_NAME GTH_POTENTIALS</font></div><div><font face="courier new, monospace" size="2"> &QS</font></div><div><font face="courier new, monospace" size="2"> EPS_DEFAULT 1.0E-10</font></div><div><font face="courier new, monospace" size="2"> &END QS</font></div><div><font face="courier new, monospace" size="2"> &MGRID</font></div><div><font face="courier new, monospace" size="2"> NGRIDS 4</font></div><div><font face="courier new, monospace" size="2"> CUTOFF 300</font></div><div><font face="courier new, monospace" size="2"> REL_CUTOFF 60</font></div><div><font face="courier new, monospace" size="2"> &END MGRID</font></div><div><font face="courier new, monospace" size="2"> &XC</font></div><div><font face="courier new, monospace" size="2"> &XC_FUNCTIONAL PADE</font></div><div><font face="courier new, monospace" size="2"> &END XC_FUNCTIONAL</font></div><div><font face="courier new, monospace" size="2"> &END XC</font></div><div><font face="courier new, monospace" size="2"> &SCF</font></div><div><font face="courier new, monospace" size="2"> SCF_GUESS ATOMIC</font></div><div><font face="courier new, monospace" size="2"> EPS_SCF 1.0E-7</font></div><div><font face="courier new, monospace" size="2"> MAX_SCF 300</font></div><div><font face="courier new, monospace" size="2"> ADDED_MOS 10</font></div><div><font face="courier new, monospace" size="2"> &DIAGONALIZATION ON</font></div><div><font face="courier new, monospace" size="2"> ALGORITHM STANDARD</font></div><div><font face="courier new, monospace" size="2"> &END DIAGONALIZATION</font></div><div><font face="courier new, monospace" size="2"> &MIXING T</font></div><div><font face="courier new, monospace" size="2"> METHOD BROYDEN_MIXING</font></div><div><font face="courier new, monospace" size="2"> ALPHA 0.4</font></div><div><font face="courier new, monospace" size="2"> NBROYDEN 8</font></div><div><font face="courier new, monospace" size="2"> &END MIXING</font></div><div><font face="courier new, monospace" size="2"> &SMEAR ON</font></div><div><font face="courier new, monospace" size="2"> METHOD FERMI_DIRAC</font></div><div><font face="courier new, monospace" size="2"> ELECTRONIC_TEMPERATURE [K] 300</font></div><div><font face="courier new, monospace" size="2"> &END SMEAR</font></div><div><font face="courier new, monospace" size="2"> &END SCF</font></div><div><font face="courier new, monospace" size="2"> &END DFT</font></div><div><font face="courier new, monospace" size="2"> &PRINT</font></div><div><font face="courier new, monospace" size="2"> &FORCES ON</font></div><div><font face="courier new, monospace" size="2"> &END FORCES</font></div><div><font face="courier new, monospace" size="2"> &END PRINT</font></div><div><font face="courier new, monospace" size="2">&END FORCE_EVAL</font></div></div><div><font face="courier new, monospace" size="2"><br></font></div><div><font face="courier new, monospace" size="2">***</font></div><div><font face="courier new, monospace" size="2"><br></font></div><div><font face="courier new, monospace" size="2">This yields a total energy of E1=-35.155 a.u. after convergence.</font></div><div><font face="courier new, monospace" size="2"><br></font></div><div><font face="courier new, monospace" size="2">Then I decided to calculate the "vacuum" energy of an isolated atom, input below:</font></div><div><font face="courier new, monospace" size="2"><br></font></div><div><font face="courier new, monospace" size="2"><div>&GLOBAL</div><div> PROJECT Ni_inp_test</div><div> RUN_TYPE ENERGY_FORCE</div><div> PRINT_LEVEL LOW</div><div>&END GLOBAL</div><div>&FORCE_EVAL</div><div> METHOD Quickstep</div><div> &SUBSYS</div><div> &KIND Ni</div><div> ELEMENT<span class="Apple-tab-span" style="white-space:pre"> </span>Ni</div><div> BASIS_SET DZV-GTH-PADE-q18</div><div> POTENTIAL GTH-PADE-q10</div><div> &END KIND</div><div> &CELL</div><div> A 30.00000 0.000000 0.000000</div><div> B 0.000000 30.00000 0.000000</div><div> C<span class="Apple-tab-span" style="white-space:pre"> </span> 0.000000 0.000000 30.00000</div><div> &END CELL</div><div> &COORD</div><div> Ni 0.000000000 0.000000000 0.000000000</div><div> &END COORD</div><div> &END SUBSYS</div><div> &DFT</div><div> BASIS_SET_FILE_NAME BASIS_SET</div><div> POTENTIAL_FILE_NAME GTH_POTENTIALS</div><div> &QS</div><div> EPS_DEFAULT 1.0E-10</div><div> &END QS</div><div> &MGRID</div><div> NGRIDS 4</div><div> CUTOFF 300</div><div> REL_CUTOFF 60</div><div> &END MGRID</div><div> &XC</div><div> &XC_FUNCTIONAL PADE</div><div> &END XC_FUNCTIONAL</div><div> &END XC</div><div> &SCF</div><div> SCF_GUESS ATOMIC</div><div> EPS_SCF 1.0E-7</div><div> MAX_SCF 300</div><div> ADDED_MOS 10</div><div> &DIAGONALIZATION ON</div><div> ALGORITHM STANDARD</div><div> &END DIAGONALIZATION</div><div> &MIXING T</div><div> METHOD BROYDEN_MIXING</div><div> ALPHA 0.4</div><div> NBROYDEN 8</div><div> &END MIXING</div><div> &SMEAR ON</div><div> METHOD FERMI_DIRAC</div><div> ELECTRONIC_TEMPERATURE [K] 300</div><div> &END SMEAR</div><div> &END SCF</div><div> &END DFT</div><div> &PRINT</div><div> &FORCES ON</div><div> &END FORCES</div><div> &END PRINT</div><div>&END FORCE_EVAL</div><div><br></div><div>***</div><div><br></div><div>This also converges and yields a total energy E2=-34.555 a.u.</div><div><br></div><div><br></div><div>Hence, my questions:</div><div><br></div><div>1. Is this even the correct way of calculating what I want, including the energy calculations, XC functional, and basis?</div><div>2. Should the spin properties be explicitly set in the input? There are none now.</div><div>3. Am I setting up the FCC lattice correctly (first input file)? My translation vectors are set by the ABC values, but I have no idea whether this is right.</div><div>4. If the first simulation yields the total energy of the system and the FCC lattice implies 12 nearest neighbors, then removing the center would change the total energy by (E1-E2)/6, which isn't the experimental -4.4 eV. Am I completely off track here? :)</div><div><br></div><div>Thanks a lot!</div></font></div>