[DFTB-Plus-User] error for reading charge

[Ben Hourahine]

Hello Hongsheng,

this is due to a drift in the mixer output charges, and can often
indicate an instability in the SCC cycle.

There will eventually be an option to disable this check in the next
code release, but for the moment, you may be able to side step this by
setting the expected charge to be very slightly positive, as the
charge.bin file contains data with a net charge of
10000.000000-9999.987357, so

Charge = .012643

An alternative option for the current master branch on github is to use
text based restart files for the charge, and you can edit those to
correct the missing electron fraction.

Regards

Ben


On 28/06/18 13:15, Hongsheng Liu wrote:
> Dear DFTB+ users,
>   I am performing some DFTB calculations for a magnetic system with
> DFTB+17.1. When I stop the calculation and restart it with reading the
> charges.bin file, I got an error as below:
> ERROR!
> -> External file of charges has a total charge:       9999.987357,
> instead of       10000.000000
>
> My input is listed below:
> Geometry = GenFormat {
>  <<< "geo_end.gen"
> }
> Driver = {}
> Hamiltonian = DFTB {
>  SCC = Yes
>  SCCTolerance = 1e-3
>  MAXSCCIterations = 2000
>  OrbitalResolvedSCC = Yes
>  Mixer = Anderson {
>  MixingParameter = 0.02
>  DynMixingParameters = {
>  3.0e-3 0.03
>  3.0e-4 0.15
>  4.0e-5 0.2
>  }
>  }
> ......
>  SpinPolarisation = Colinear {
>  UnpairedElectrons = 1194
>  RelaxTotalSpin = No
>  }
>  ReadInitialCharges = Yes
>   PolynomialRepulsive = {
> .....
>  }
>  OrbitalPotential = {
>   Functional = {FLL}
>   Fe = {
>    Shells = 3
>    UJ = 0.129
>    }
>   }
>  SpinConstants = {
> ......
> }
>  Eigensolver = RelativelyRobust {}
>  Filling = Fermi {
>  Temperature [K] = 300
>  }
>  SlaterKosterFiles = Type2FileNames {
>  Prefix = "./"
>  Separator = "-"
>  Suffix = ".skf"
>  }
> }
>
> The system is neutral and I did not set the total charge in the input
> file. This error happens sometimes, not always. This error happens
> also for DFTB+18.1. This never happens for DFTB+1.3. But DFTB+1.3 is
> slow. Do anybody have the same problem? Any suggestion is welcomed.
> Thank you.
>
> All the best,
> Hongsheng Liu
>
>
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-- 
      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

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