<div dir="ltr"><div><span style="font-family: verdana, sans-serif;"> Hi everyone, </span></div><div><font face="verdana,sans-serif"> I have been trying to calculate the band structure of bilayer graphene using CP2k 4.1. The input file follow the tutorial <a href="https://www.cp2k.org/exercises:2016_uzh_cmest:band_structure_calculation?s[]=graphene">band structure of graphene</a> , and is listed in the following <br></font></div><div><font face="verdana,sans-serif"><br></font></div><div style="background-color: rgb(250, 250, 250); border-color: rgb(187, 187, 187); border-style: solid; border-width: 1px; overflow-wrap: break-word;" class="prettyprint"><code class="prettyprint"><div class="subprettyprint"><span style="color: #660;" class="styled-by-prettify"></span><code class="prettyprint"><span style="color: #660;" class="styled-by-prettify">&GLOBAL<br>  PROJECT twoLayerGraphBS_z18<br>  RUN_TYPE ENERGY<br>  PRINT_LEVEL MEDIUM<br>&END GLOBAL<br><br>&FORCE_EVAL<br>  METHOD Quickstep<br>  &DFT<br>    BASIS_SET_FILE_NAME BASIS_MOLOPT<br>    POTENTIAL_FILE_NAME POTENTIAL<br><br>    &POISSON<br>      PERIODIC XYZ <br>    &END POISSON<br>    &QS <br>      EXTRAPOLATION USE_GUESS<br>    &END QS<br>    &SCF<br>      SCF_GUESS ATOMIC<br>      EPS_SCF 1.0E-6<br>      MAX_SCF 300 <br><br>      ADDED_MOS 2<br>      &SMEAR ON<br>        METHOD FERMI_DIRAC<br>        ELECTRONIC_TEMPERATURE [K] 300 <br>      &END SMEAR<br>      &DIAGONALIZATION<br>        ALGORITHM STANDARD<br>        EPS_ADAPT 0.01<br>      &END DIAGONALIZATION<br>      &MIXING<br>        METHOD BROYDEN_MIXING<br>        ALPHA 0.2<br>        BETA 1.5<br>        NBROYDEN 8<br>      &END MIXING<br>    &END SCF<br><br>    &XC<br>      &XC_FUNCTIONAL PBE<br>      &END XC_FUNCTIONAL<br>    &END XC<br>    &KPOINTS<br>      SCHEME MONKHORST-PACK 3 3 1<br>      SYMMETRY OFF<br>      WAVEFUNCTIONS REAL<br>      FULL_GRID .TRUE.<br>      PARALLEL_GROUP_SIZE 0<br>      &BAND_STRUCTURE<br>        ADDED_MOS 6<br>        FILE_NAME graph_z18.bs<br>        &KPOINT_SET<br>          UNITS CART_BOHR<br>          SPECIAL_POINT 0.0 0.0 0.0<br>          SPECIAL_POINT 1./2. 0.0 0.0<br>          SPECIAL_POINT 2./3. 1./3. 0.0<br>          SPECIAL_POINT 0.0 0.0 0.0<br>          NPOINTS 80  <br>        &END<br>      &END BAND_STRUCTURE<br>    &END KPOINTS<br>    &PRINT<br>        &E_DENSITY_CUBE ON<br>            STRIDE 1 1 1<br>        &END E_DENSITY_CUBE<br>    &END PRINT<br>  &END DFT<br>  &SUBSYS<br>    &CELL<br>      ABC [angstrom] 2.4612 2.4612 21.0<br>      ALPHA_BETA_GAMMA 90. 90. 60.<br>      SYMMETRY HEXAGONAL<br>      PERIODIC XYZ<br>      MULTIPLE_UNIT_CELL 1 1 1<br>    &END CELL<br>    &TOPOLOGY<br>      MULTIPLE_UNIT_CELL 1 1 1<br>    &END TOPOLOGY<br>    &COORD<br>      SCALED<br>      C 1./3. 1./3. 0.<br>      C 2./3. 2./3. 0.<br>      C 2./3. 2./3. 1./6.<br>      C 3./3. 3./3. 1./6.<br>    &END<br>    &KIND C<br>      ELEMENT C<br>      BASIS_SET TZVP-MOLOPT-GTH<br>      POTENTIAL GTH-PBE-q4<br>    &END KIND<br>  &END SUBSYS<br><br>&END FORCE_EVAL<br><br><br><br></span></code></div></code></div><br><div>And the band structure I plotted is as follows</div><p class="separator" style="text-align: center; clear: both;"><a imageanchor="1" href="https://lh3.googleusercontent.com/-KWZPrTYUGBs/W0WoPcsrDaI/AAAAAAAAABE/cLd4uxyz8WA36prGTQDk24w8y_XR_sP-QCLcBGAs/s1600/bilayerGraph.png" style="margin-left: 1em; margin-right: 1em;"><img style="" src="https://lh3.googleusercontent.com/-KWZPrTYUGBs/W0WoPcsrDaI/AAAAAAAAABE/cLd4uxyz8WA36prGTQDk24w8y_XR_sP-QCLcBGAs/s320/bilayerGraph.png" width="320" height="240" border="0"></a></p><div>The k-point path I choose is : \gamma->M->K->\gamma. There should not exist band gap near the point K and the profile of the line near point K should be parabola. <br></div><div>Does anyone know where is the problem in my calculation setting ?</div><div><br></div><div>Thanks for any kind response !<br></div><div><br></div></div>