[DFTB-Plus-User] TD-DFTB

[Roozbeh Anvari]

Hi Franco ,

Thank you for your help,

Best regards
Roozbeh


On Thu, Feb 17, 2022 at 9:32 PM Franco Bonafé <francobonafe at gmail.com>
wrote:

> Dear Roozbeh Anvari,
>
> The warning comes because you are using a periodic structure, and the
> currently implemented dipole coupling only works either for non-periodic
> structures, or when the electric field is polarized in non-periodic
> directions (e.g., directions in which the geometry has a large vacuum
> region between periodic images). In your case, for example, your field's
> polarization vector is (0,1,0), and judging by the number of k-points that
> you are using in your sampling, I guess your structure is really periodic
> in the (0,1,0) direction. Hence, this would not give physically meaningful
> results. If you are dealing with a slab that is, for example, parallel to
> the xy plane, then you could polarize your electric field in the (0,0,1)
> direction. We plan to implement other coupling methods to the Hamiltonian,
> which will allow for laser fields polarized in periodic dimensions, but
> this is currently not possible.
>
> The error message is something completely different, namely due to your
> attempt to run Ehrenfest (ion) dynamics in periodic systems sampling
> several k-points. This is not implemented yet and then it's not possible.
> An alternative would be to use a supercell that allows you to run a Gamma
> point-only calculation, for which ion dynamics in principle works.
>
> Best regards,
> Franco
>
>
> El jue, 17 feb 2022 a las 11:35, Roozbeh Anvari (<roozbeh.anvari at gmail.com>)
> escribió:
>
>> Dear DFTB+ community,
>>
>> I am wondering why I am getting the following warning and error message,
>>
>> Thank you for your help,
>> Roozbeh Anvari
>> PDF, Physics, Queen's University , Canada
>>
>>
>> WARNING!
>> -> Polarization components of the laser in a periodic direction do not
>> work.  Make sure you are polarizing the field in non-periodic directions.
>> ERROR!
>> -> Ion dynamics is not implemented yet for imaginary Hamiltonians.
>> ERROR STOP
>>
>> ----------------------------------------------
>>
>> Geometry = GenFormat {
>>   <<< coords.gen
>> }
>>
>> Driver = {}
>> Hamiltonian = DFTB {
>>   SCC = Yes
>>   SCCTolerance = 1e-8  # default : 1e-5
>>   MaxAngularMomentum = {
>>     C = "p"
>>  }
>>   Filling = Fermi {
>>     Temperature [Kelvin] = 100
>>   }
>>   SlaterKosterFiles =   {
>>   C-C="../pbc-0-3/C-C.skf"
>>   }
>>
>>   KPointsAndWeights = SuperCellFolding {
>>     20 0 0
>>     0 20 0
>>     0 0 1
>>     0.5 0.5 0.0
>>   }
>>
>>   Dispersion = LennardJones{
>>    Parameters = UFFParameters{}
>>   }
>> }
>>
>> InputVersion = 21.2
>> ElectronDynamics = {
>> Steps = 50000
>> TimeStep = 0.1
>> FieldStrength [v/a] = 0.01
>> Perturbation = Laser {
>> PolarizationDirection = 0 1 0
>> LaserEnergy [ev] = 2.55
>> }
>> EnvelopeShape = Sin2 {
>> Time1 [fs] = 30.0
>> }
>> Populations = Yes
>> IonDynamics = Yes
>> InitialTemperature [k] = 0.0
>> Pump = Yes
>> PumpProbeFrames = 1000
>> PumpProbeRange [fs] = 0.0 50.0
>> EulerFrequency = 200
>> }
>>
>>
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>>
>
>
> --
> Dr. Franco P. Bonafé
> *http://francobonafe.weebly.com <http://francobonafe.weebly.com>*
>
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