[CP2K:10517] Something confusing in the calculation of bilayer graphene

[hut... at chem.uzh.ch]

Hi

the current version (released) of cp2k is 6.1.
I only say that this option has not been fully tested and
you better use the current version. 

You can always get the Brillouin zone sampling by using
k-points, supercell, or a combination of both.

regards

Juerg Hutter 
--------------------------------------------------------------
Juerg Hutter                         Phone : ++41 44 635 4491
Institut für Chemie C                FAX   : ++41 44 635 6838
Universität Zürich                   E-mail: hut... at chem.uzh.ch
Winterthurerstrasse 190
CH-8057 Zürich, Switzerland
---------------------------------------------------------------

-----cp... at googlegroups.com wrote: -----
To: "cp2k" <cp... at googlegroups.com>
From: "Tianshu Jiang in Beijing" 
Sent by: cp... at googlegroups.com
Date: 07/13/2018 05:03AM
Subject: Re: [CP2K:10517] Something confusing in the calculation of bilayer graphene

Hi, jgh

Thanks for your reply !  
Do you mean that I cannot do such a calculation using the current CP2K version ? Or I need to change the position of all k-points ?
Waiting for your more detailed response.

Meanwhile, I also have interest in defective graphene. But in mu calculation in CP2K, if I use a supercell to calculate the band structure of graphene, 
the SCF doesn't converge.  I have found a paper relating the calculation of band structure in graphene and h-BN, but the code they use is VASP. 
Their simulation also select a supercell and a 12*12*1 k-mesh.
I want to know does there exists the corresponding setting in CP2K ? How should I find ?

I would appreciate your patient reply !

在 2018年7月12日星期四 UTC+8下午3:14:31，jgh写道：Hi 
 
this is still a rather untested option in CP2K. It might well 
be that for non-cubic cells there are still problems with the 
definition of k-point paths. This is especially true for older 
versions (pre 5.1). 
You can try to compare to the results if you use the special 
points in the SCF settings. 
 
regards 
 
Juerg Hutter 
-------------------------------------------------------------- 
Juerg Hutter                         Phone : ++41 44 635 4491 
Institut für Chemie C                FAX   : ++41 44 635 6838 
Universität Zürich                   E-mail: hut... at chem.uzh.ch 
Winterthurerstrasse 190 
CH-8057 Zürich, Switzerland 
--------------------------------------------------------------- 
 
-----cp... at googlegroups.com wrote: ----- 
To: "cp2k" <cp... at googlegroups.com> 
From: "Tianshu Jiang in Beijing"  
Sent by: cp... at googlegroups.com 
Date: 07/11/2018 08:53AM 
Subject: [CP2K:10502] Something confusing in the calculation of bilayer graphene 
 
 Hi everyone,  
 I have been trying to calculate the band structure of bilayer graphene using CP2k 4.1. The input file follow the tutorial band structure of graphene , and is listed in the following  
 
&GLOBAL 
  PROJECT twoLayerGraphBS_z18 
  RUN_TYPE ENERGY 
  PRINT_LEVEL MEDIUM 
&END GLOBAL 
 
&FORCE_EVAL 
  METHOD Quickstep 
  &DFT 
    BASIS_SET_FILE_NAME BASIS_MOLOPT 
    POTENTIAL_FILE_NAME POTENTIAL 
 
    &POISSON 
      PERIODIC XYZ  
    &END POISSON 
    &QS  
      EXTRAPOLATION USE_GUESS 
    &END QS 
    &SCF 
      SCF_GUESS ATOMIC 
      EPS_SCF 1.0E-6 
      MAX_SCF 300  
 
      ADDED_MOS 2 
      &SMEAR ON 
        METHOD FERMI_DIRAC 
        ELECTRONIC_TEMPERATURE [K] 300  
      &END SMEAR 
      &DIAGONALIZATION 
        ALGORITHM STANDARD 
        EPS_ADAPT 0.01 
      &END DIAGONALIZATION 
      &MIXING 
        METHOD BROYDEN_MIXING 
        ALPHA 0.2 
        BETA 1.5 
        NBROYDEN 8 
      &END MIXING 
    &END SCF 
 
    &XC 
      &XC_FUNCTIONAL PBE 
      &END XC_FUNCTIONAL 
    &END XC 
    &KPOINTS 
      SCHEME MONKHORST-PACK 3 3 1 
      SYMMETRY OFF 
      WAVEFUNCTIONS REAL 
      FULL_GRID .TRUE. 
      PARALLEL_GROUP_SIZE 0 
      &BAND_STRUCTURE 
        ADDED_MOS 6 
        FILE_NAME graph_z18.bs 
        &KPOINT_SET 
          UNITS CART_BOHR 
          SPECIAL_POINT 0.0 0.0 0.0 
          SPECIAL_POINT 1./2. 0.0 0.0 
          SPECIAL_POINT 2./3. 1./3. 0.0 
          SPECIAL_POINT 0.0 0.0 0.0 
          NPOINTS 80   
        &END 
      &END BAND_STRUCTURE 
    &END KPOINTS 
    &PRINT 
        &E_DENSITY_CUBE ON 
            STRIDE 1 1 1 
        &END E_DENSITY_CUBE 
    &END PRINT 
  &END DFT 
  &SUBSYS 
    &CELL 
      ABC [angstrom] 2.4612 2.4612 21.0 
      ALPHA_BETA_GAMMA 90. 90. 60. 
      SYMMETRY HEXAGONAL 
      PERIODIC XYZ 
      MULTIPLE_UNIT_CELL 1 1 1 
    &END CELL 
    &TOPOLOGY 
      MULTIPLE_UNIT_CELL 1 1 1 
    &END TOPOLOGY 
    &COORD 
      SCALED 
      C 1./3. 1./3. 0. 
      C 2./3. 2./3. 0. 
      C 2./3. 2./3. 1./6. 
      C 3./3. 3./3. 1./6. 
    &END 
    &KIND C 
      ELEMENT C 
      BASIS_SET TZVP-MOLOPT-GTH 
      POTENTIAL GTH-PBE-q4 
    &END KIND 
  &END SUBSYS 
 
&END FORCE_EVAL 
 
 
 
 
And the band structure I plotted is as follows 
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.  
Does anyone know where is the problem in my calculation setting ? 
 
Thanks for any kind response ! 
 
   
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