Hybrid functional calculation results show large difference with VASP

[Marcella Iannuzzi]

Hi, 

Your eps_schwarz at 1.0e-6 is far too large.
The default is 1.0e-10. 

Regards
Marcella

On Monday, September 18, 2017 at 5:07:21 PM UTC+2, Xiaoming Wang wrote:
>
> Hello,
>
> I conducted PBE0 and HSE calculations on a cube of ~10*10*10 (perovskite). 
> For comparison, I also did the calculations using VASP (gamma only). 
> However, to my surprise, the band gap obtained by cp2k is about 0.5 eV 
> (HSE)  and 0.8 eV(PBE0) smaller than by vasp. The vasp results agree well 
> with literature. For the cp2k calculations, I have checked the convergence 
> of the cutoffs and auxiliary basis sets. Since for my structure, the only 
> available basis sets is DZVP within BASIS_MOLOPT, thus I could not find a 
> way to increase the primary basis size. But I checked the PBE results with 
> DZVP compared with those of VASP. The difference of the band gap is very 
> small, say only 0.02 eV. So I think the DZVP basis set is OK for my system. 
> The inputs of my calculations are as follows. Could anyone give me some 
> suggestions?
>
> HSE input:
> --------------------------------------------------------------------
> &GLOBAL
>  PROJECT_NAME CsInAgCl
>  RUN_TYPE ENERGY
>  PRINT_LEVEL LOW
> &END GLOBAL
>
> &FORCE_EVAL
>  METHOD QS
>   &DFT
>     BASIS_SET_FILE_NAME BASIS_MOLOPT
>     BASIS_SET_FILE_NAME BASIS_ADMM
>     BASIS_SET_FILE_NAME BASIS_ADMM_MOLOPT
>     POTENTIAL_FILE_NAME GTH_POTENTIALS
>     WFN_RESTART_FILE_NAME -PBE.wfn
>     &QS
>      EPS_PGF_ORB 1.0e-6
>     &END
>     &MGRID
>       CUTOFF 250
>       REL_CUTOFF 60
>     &END MGRID
>     &XC
>       &XC_FUNCTIONAL
>        &PBE
>         SCALE_X 0.0
>         SCALE_C 1.0
>        &END PBE
>        &XWPBE
>         SCALE_X -0.25
>         SCALE_X0 1.0
>         OMEGA 0.11
>        &END XWPBE
>       &END XC_FUNCTIONAL
>       &HF
>        FRACTION 0.25
>        &SCREENING
>         EPS_SCHWARZ 1.0e-6
>        &END SCREENING
>        &INTERACTION_POTENTIAL
>         POTENTIAL_TYPE SHORTRANGE
>         OMEGA 0.11
>        &END INTERACTION_POTENTIAL
>        &MEMORY
>         MAX_MEMORY 2400
>         EPS_STORAGE_SCALING 0.1
>        &END MEMORY
>       &END HF
>     &END XC
>     &SCF
>      #ADDED_MOS 2
>       MAX_SCF 100
>       EPS_SCF 1.0e-6
>       CHOLESKY INVERSE
>       SCF_GUESS RESTART
>       &OT
>        PRECONDITIONER FULL_ALL
>        ENERGY_GAP 0.01
>       &END OT
>     &END SCF
>     &AUXILIARY_DENSITY_MATRIX_METHOD
>      METHOD BASIS_PROJECTION
>      ADMM_PURIFICATION_METHOD MO_DIAG
>     &END AUXILIARY_DENSITY_MATRIX_METHOD
>     &PRINT
>      &MO_CUBES
>       WRITE_CUBE F
>       NHOMO 1
>       NLUMO 1
>      &END MO_CUBES
>     &END PRINT
>   &END DFT
>   &SUBSYS
>     &CELL
>       ABC [angstrom] 10.5345 10.5345 10.5345
>       ALPHA_BETA_GAMMA [deg] 90 90 90
>       PERIODIC XYZ
>       SYMMETRY CUBIC
>     &END CELL
>     &COORD
>      ....[I omitted the coors here ]
>       SCALED T
>     &END COORD
>     &KIND Cs
>       ELEMENT Cs
>       BASIS_SET DZVP-MOLOPT-SR-GTH
>       AUX_FIT_BASIS_SET FIT11
>       POTENTIAL GTH-PBE-q9
>     &END KIND
>     &KIND In
>       ELEMENT In
>       BASIS_SET DZVP-MOLOPT-SR-GTH
>       AUX_FIT_BASIS_SET FIT11
>       POTENTIAL GTH-PBE-q13
>     &END KIND
>     &KIND Ag
>       ELEMENT Ag
>       BASIS_SET DZVP-MOLOPT-SR-GTH
>       AUX_FIT_BASIS_SET FIT11
>       POTENTIAL GTH-PBE-q11
>     &END KIND
>     &KIND Cl
>       ELEMENT Cl
>       BASIS_SET DZVP-MOLOPT-SR-GTH
>       AUX_FIT_BASIS_SET FIT3
>       POTENTIAL GTH-PBE-q7
>     &END KIND
>   &END SUBSYS
> &END FORCE_EVAL
>
> -----------------------------------------------------------------------------------------------
>
> PBE0 input
>
>
> --------------------------------------------------------
> &GLOBAL
>  PROJECT_NAME CsInAgCl
>  RUN_TYPE ENERGY
>  PRINT_LEVEL LOW
> &END GLOBAL
> &FORCE_EVAL
>  METHOD QS
>   &DFT
>     BASIS_SET_FILE_NAME BASIS_MOLOPT
>     BASIS_SET_FILE_NAME BASIS_ADMM
>     BASIS_SET_FILE_NAME BASIS_ADMM_MOLOPT
>     POTENTIAL_FILE_NAME GTH_POTENTIALS
>     WFN_RESTART_FILE_NAMEPBE.wfn
>     &QS
>      EPS_PGF_ORB 1.0e-6
>     &END
>     &MGRID
>       CUTOFF 250
>       REL_CUTOFF 60
>     &END MGRID
>     &XC
>       &XC_FUNCTIONAL
>        &PBE
>         SCALE_X 0.75
>         SCALE_C 1.0
>        &END PBE
>        &PBE_HOLE_T_C_LR
>         CUTOFF_RADIUS 5.25
>         SCALE_X 0.25
>        &END PBE_HOLE_T_C_LR
>       &END XC_FUNCTIONAL
>       &HF
>        FRACTION 0.25
>        &SCREENING
>         EPS_SCHWARZ 1.0e-6
>        &END SCREENING
>        &INTERACTION_POTENTIAL
>         POTENTIAL_TYPE TRUNCATED
>         CUTOFF_RADIUS 5.25
>         T_C_G_DATA ./t_c_g.dat
>        &END INTERACTION_POTENTIAL
>        &MEMORY
>         MAX_MEMORY 2400
>         EPS_STORAGE_SCALING 0.1
>        &END MEMORY
>       &END HF
>     &END XC
>     &SCF
>       MAX_SCF 100
>       EPS_SCF 1.0e-6
>       CHOLESKY INVERSE
>       SCF_GUESS RESTART
>       &OT
>        PRECONDITIONER FULL_ALL
>        ENERGY_GAP 0.01
>       &END OT
>     &END SCF
>     &AUXILIARY_DENSITY_MATRIX_METHOD
>      METHOD BASIS_PROJECTION
>      ADMM_PURIFICATION_METHOD MO_DIAG
>     &END AUXILIARY_DENSITY_MATRIX_METHOD
>     &PRINT
>      &MO_CUBES
>       WRITE_CUBE F
>       NHOMO 1
>       NLUMO 1
>      &END MO_CUBES
>     &END PRINT
>   &END DFT
>   &SUBSYS
>     &CELL
>       ABC [angstrom] 10.5345 10.5345 10.5345
>       ALPHA_BETA_GAMMA [deg] 90 90 90
>       PERIODIC XYZ
>       SYMMETRY CUBIC
>     &END CELL
>     &COORD
>        .......
>       SCALED T
>     &END COORD
>     &KIND Cs
>       ELEMENT Cs
>       BASIS_SET DZVP-MOLOPT-SR-GTH
>       AUX_FIT_BASIS_SET FIT11
>       POTENTIAL GTH-PBE-q9
>     &END KIND
>     &KIND In
>       ELEMENT In
>       BASIS_SET DZVP-MOLOPT-SR-GTH
>       AUX_FIT_BASIS_SET FIT11
>       POTENTIAL GTH-PBE-q13
>     &END KIND
>     &KIND Ag
>       ELEMENT Ag
>       BASIS_SET DZVP-MOLOPT-SR-GTH
>       AUX_FIT_BASIS_SET FIT11
>       POTENTIAL GTH-PBE-q11
>     &END KIND
>     &KIND Cl
>       ELEMENT Cl
>       BASIS_SET DZVP-MOLOPT-SR-GTH
>       AUX_FIT_BASIS_SET FIT3
>       POTENTIAL GTH-PBE-q7
>     &END KIND
>   &END SUBSYS
> &END FORCE_EVAL
>
> --------------------------------------
>
>
>
>
> Best,
>
> Xiaoming Wang
>
>
>   
>
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