[DFTB-Plus-User] [RE]Re: error in agr-scc transport

Benjamin Hourahine benjamin.hourahine at strath.ac.uk
Thu Aug 11 10:01:06 CEST 2022


Hello Min,

Could you send me the actual geometry as well off list? And yes, the Poissonbox entry is not relevant for supercells.

Regards

Ben

       Dr. B. Hourahine, SUPA, Department of Physics,
     University of Strathclyde, John Anderson Building,
             107 Rottenrow, Glasgow G4 0NG, UK.
     +44 141 548 2325, benjamin.hourahine at strath.ac.uk

2013/4 THE Awards Entrepreneurial University of the Year
       2012/13 THE Awards UK University of the Year

    The University of Strathclyde is a charitable body,
         registered in Scotland, number SC015263
________________________________
From: DFTB-Plus-User <dftb-plus-user-bounces at mailman.zfn.uni-bremen.de> on behalf of 민제홍 <alswpghd1 at inu.ac.kr>
Sent: 11 August 2022 05:57
To: User list for DFTB+ related questions <dftb-plus-user at mailman.zfn.uni-bremen.de>
Subject: [DFTB-Plus-User] [RE]Re: error in agr-scc transport


Dear Dr. Hourahine,


I really appreciated with your suggestion.

I was about to calculating grephene field effect transistor in which the transverse to the transport direction is periodic.

When I tried to calculate supercell transport with this Poisson solver setting in dftb_in.hsd file,


 Electrostatics = Poisson {

    Poissonbox [Angstrom] = 40.0 30.0 30.0

    MinimalGrid [Angstrom] = 0.5 0.5 0.5

    SavePotential = Yes

    Gate = Planar{

      GateLength_l [Angstrom] = 30

      GateLength_t [Angstrom] = 30

      GateDistance [Angstrom] = 5

      GatePotential [eV] = 6

    }

  }


the error is below.


Reading SK-files:

../../slako/C-C.skf

Done.

WARNING!

-> The following 1 node(s) have been ignored by the parser:

(1)

Path: dftbplusinput/Hamiltonian/DFTB/Electrostatics/Poisson/Poissonbox

Line: 48-48 (File: dftb_in.hsd)          //  "Poissonbox [Angstrom] = 40.0 30.0 30.0"


ERROR!

-> Code halting due to the presence of errors in dftb_in file.


From this error I thought that in supercell calculating, 'Poissonbox [Angstrom]' code is not in use,

so I changed the codes like this


Electrostatics = Poisson {

    MinimalGrid [Angstrom] = 0.5 0.5 0.5

    SavePotential = Yes

    Gate = Planar{

      GateLength_l [Angstrom] = 30

      GateLength_t [Angstrom] = 30

      GateDistance [Angstrom] = 5

      GatePotential [eV] = 6

    }

  }


In this case, the error is below.


ERROR!

-> Poisson solver error n=-3


This error(n=-3) still occurs when I change the values of MinimalGrid.
And I'll show whole codes in dftb_in.hsd in order to give you detail info.

Geometry = GenFormat {
<<< 'Ordered_g.gen'      //supercell in which transport direction is z direction.
}

Transport {
    Device {
      AtomRange = 1 128
      FirstLayerAtoms =  1 65
    }
    Contact {
      Id = "source"
      AtomRange = 129 256
      FermiLevel [eV] = -4.35
      Potential [eV] = 0
    }
    Contact {
      Id = "drain"
      AtomRange = 257 384
      FermiLevel [eV] = -4.35
      Potential [eV] = 0.1
    }
    Task = UploadContacts {
  }
}


Hamiltonian = DFTB {
  SCC = Yes
  SCCTolerance = 1E-6
  ReadInitialCharges = No
  MaxAngularMomentum = {
    C = "p"
  }

  SlaterKosterFiles = Type2FileNames {
  Prefix = "../../slako/"
  Separator = "-"
  Suffix = ".skf"
  }
  KpointsAndWeights = SupercellFolding {
   10 0 0
   0 1 0
   0 0 1
   0 0 0
   }

  Electrostatics = Poisson {
    Poissonbox [Angstrom] = 30 400 30
    MinimalGrid [Angstrom] = 0.5 0.5 0.5
    SavePotential = Yes

    Gate = Planar{
       GateLength_t [Angstrom] = 400
       GateDistance [Angstrom] = 0.1
       GatePotential [eV] = 1
       }
   }
  Solver = GreensFunction {}

  Mixer = Broyden {
    MixingParameter = 0.02
  }
}

Analysis = {
  TunnelingAndDos {
    Verbosity = 101
    EnergyRange [eV] = -6.0 -3.0
    EnergyStep [eV] = 0.01
  }
}

ParserOptions {
  ParserVersion = 7
}

I'll be really thankful If you can help me how to solve this problem.

Best regards,
Min

----- Original Message -----
From : Benjamin Hourahine <benjamin.hourahine at strath.ac.uk>
To : "dftb-plus-user at mailman.zfn.uni-bremen.de" <dftb-plus-user at mailman.zfn.uni-bremen.de>
Cc :
Sent : 2022-08-10 02:31:24
Subject : Re: [DFTB-Plus-User] error in agr-scc transport


Hello Min,

Looking at the code underneath the Poisson solver, this seems to be an error for the grid spacing being too small (though I'm not so familiar with that code section).

What settings are you using for the Poisson solver and the rest of the calculation (you did not give much detail)?

Regards

Ben

       Dr. B. Hourahine, SUPA, Department of Physics,
     University of Strathclyde, John Anderson Building,
             107 Rottenrow, Glasgow G4 0NG, UK.
     +44 141 548 2325, benjamin.hourahine at strath.ac.uk

2013/4 THE Awards Entrepreneurial University of the Year
       2012/13 THE Awards UK University of the Year

    The University of Strathclyde is a charitable body,
         registered in Scotland, number SC015263
________________________________
From: DFTB-Plus-User <dftb-plus-user-bounces at mailman.zfn.uni-bremen.de> on behalf of 민제홍 <alswpghd1 at inu.ac.kr>
Sent: 09 August 2022 11:23
To: dftb-plus-user at mailman.zfn.uni-bremen.de <dftb-plus-user at mailman.zfn.uni-bremen.de>
Subject: [DFTB-Plus-User] error in agr-scc transport

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Dear developers,


I have a problem when calculating supercell transport calculation with gate options.

Without gate options the calculation is working well, but when i put gate option such as

GatePotential [eV], the error is below;

ERROR!

-> Posson solver error n=-3

There are no specific manual or examples of gate options, I cannot find solutions about this error.

I calcutated cluster transport calculation with gate option sucessfully, but I have no idea of error in

caluating supercell with gate despite of trying to analysis the source codes.


Please give me suggestions of this problem.


Best regards,

Min

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