[DFTB-Plus-User] Fwd: Regarding MD Run.

[Bálint Aradi]

Dear Debasis,

> I have recently started a MD calculation in DFTB+ but there are certain
> numbers which I can't apprehend.
> In my input file I have specified the MD time step of 0.48 fs and the
> temperature as 2500 K, however, the
> program processing file reads:
> Starting initialization...
> --------------------------------------------------------------------------------
> Mode:                        MD without scaling of velocities
>                              (a.k.a. NVE ensemble)
> Self consistent charges:     No
> Spin polarisation:           No
> Nr. of up electrons:           420.000000
> Nr. of down electrons:         420.000000
> Periodic boundaries:         No
> Diagonalizer:                Standard
> Electronic temperature:        0.158341E-01
> Time step:                     0.198439E+02 (????)
> Temperature:                   0.791704E-02 (????)
> ----------------------------------------------------------------------
> Why are those numbers (shown in (????)) different from my input
> description, shown below:
> --------------------------------------------------------------------------
> Driver = VelocityVerlet {
>   Steps = 300
>   TimeStep [Femtosecond] = 0.48
>   Thermostat = None {
>     InitialTemperature [Kelvin] = 2500.00
>   }
> ---------------------------------------------------------------------------
> 
> Am I missing something.
> 

  DFTB+ uses for all input and output quantities atomic units (with
Hartree being the energy unit), unless specified or stated otherwise.
(This is unfortunately not that clearly written in the manual, we'll try
to improve on it for the next release ;-).) The conversion factors you
find in Appendix B.

  Best regards,

  Bálint

-- 
Dr. Bálint Aradi
Bremen Center for Computational Materials Science, University of Bremen
http://www.bccms.uni-bremen.de/en/~b_aradi


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