[DFTB-Plus-User] XLbomd

[Bálint Aradi]

Dear Jacek,

as the tblite library, which we use for the xTB functionality, does not 
offer the appropriate modified xTB expressions necessary for the XLBOMD 
dynamics, we do not support it in DFTB+ (yet).

Best regards,

Bálint


On 5/25/25 2:12 AM, Jacek Jakowski wrote:
> 
> Hi,
> 
>   I am  using  DFTB+v 24.1 compiled with xTB support and I am  trying  
> to run extended lagrangian  based  MD  with xTB  based Hamitlonian,  
> ermi  filling and for aperiodic system involving Rb and C atoms.
> It seems that everything works fine for a regular dynamics (without  
> Xlbomd section) , but  inserting a  Xlbomdfast block (or xlbomd) leads 
> to an error:
> | 
> ===============================================================================
> |
> |  DFTB+ development version (commit: 7de9470d, base: 24.1)
> |
> |  Copyright (C) 2006 - 2025  DFTB+ developers group
> |
> | 
> ===============================================================================
> |
> |  When publishing results obtained with DFTB+, please cite the following
> |  reference:
> |
> |  * DFTB+, a software package for efficient approximate density functional
> |    theory based atomistic simulations, J. Chem. Phys. 152, 124101 (2020).
> |    [doi: 10.1063/1.5143190]
> |
> |  You should also cite additional publications crediting the 
> parametrization
> |  data you use. Please consult the documentation of the SK-files for the
> |  references.
> |
> | 
> ===============================================================================
> 
> Reading input file 'dftb_in.hsd'
> Parser version: 14
> 
> --------------------------------------------------------------------------------
> ***  Converting input from parser version 10 to parser version 14 ...
> WARNING!
> -> Keyword renamed to 'PrintForces'.
> Path: dftbplusinput/Analysis/CalculateForces
> Line: 128-128 (File: dftb_in.hsd)
> 
> ***  Done.
> 
> WARNING!
> -> Settings will be read but ignored (compiled without MPI support)
> Path: dftbplusinput/Parallel
> Line: 106-106 (File: dftb_in.hsd)
> 
> WARNING!
> -> The following 1 node(s) have been ignored by the parser:
> (1)
> Path: dftbplusinput/Driver/VelocityVerlet/XlbomdFast
> Line: 92-96 (File: dftb_in.hsd)
> 
> ERROR!
> -> Code halting due to the presence of errors in dftb_in file.
> ERROR STOP
> 
> =================================
> Below is my input file:
> 
> =============================
> Geometry = genFormat {
> <<< "rb3c60-fixed-optimized.gen"
> }
> 
> Hamiltonian = xTB {
>    #Charge = +1.0
>    Method = "GFN2-xTB"
> 
>    MaxSCCIterations = 500
>    Filling = Fermi {
>            Temperature [Kelvin] = 300.0
>    }
>    KPointsAndWeights = {
>      0.0  0.0 0.0 1.0
>    }
>   #---- Extended lagrangian:
>   ForceEvaluation = Dynamics
> }
> 
> #----------   dynamics:
> Driver = VelocityVerlet {
>          #Steps = 30000
>          Steps = 30
>          TimeStep [Femtosecond] = 1.0
>          #--
>          Thermostat = none {
>             InitialTemperature [Kelvin ] = 300
>          }
>          #--
>          #Thermostat = NoseHoover {
>          #       Temperature [Kelvin] = 300
>          #       CouplingStrength [cm^-1] = 600
>          #}
>          OutputPrefix = "movie"
>          #---- extended lagrangian:
>          XlbomdFast {
>             IntegrationSteps = 5
>             Scale = 0.5
>             TransientSteps = 10
>          }
> }
> =======================
> I am wondering if it is a parser issue,  or something else?
> I would appreciate  any suggestion on how to resolve it or an example 
> input with working xlbomdfast.
> 
> Thanks so much in advance!!
> Jacek
> 
> 
> 
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-- 
Dr. Bálint Aradi
Bremen Center for Computational Materials Science, University of Bremen
http://www.uni-bremen.de/en/lmcqm/b-aradi

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