[DFTB-Plus-User] Dipole moments for periodic systems

[Benjamin Hourahine]

Hello Han-Wei Hsiao,

As the dipole moment is non-trivial to define correctly for periodic systems, this is currently disabled. The dielectric response is of course more straight forward.

You can calculate this from the second derivative of the total energy with respect to an applied field, by finite difference (the code currently traps for atomic interactions that cross the central cell discontinuity in the sawtooth field, so this may cause some challenges).

There is a development branch which directly evaluates the dielectric response using coupled perturbed formalism at:
https://github.com/bhourahine/dftbplus/tree/dynamicResponse

Which is enabled with
Analysis = {
  Polarisability = {}
}

But this is not fully completed or tested (for cells which are not orthorhomic there may still be some issues).

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 Han-Wei Hsiao <hwhsiao1 at gmail.com>
Sent: 14 December 2021 04:00
To: dftb-plus-user at mailman.zfn.uni-bremen.de <dftb-plus-user at mailman.zfn.uni-bremen.de>
Subject: [DFTB-Plus-User] Dipole moments for periodic systems

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Hello,

I’m doing some static dielectric response calculations for larger periodic systems, but it seems that dipole moment is not a standard output for periodic systems.

I was wondering if there is any way to get that information?
I would very appreciate if someone could help me with this.


Thanks! =)

Han-Wei Hsiao
Graduate Research Assistant
School of Electrical and Computer Engineering
Hall for Discovery and Learning Research
Purdue University, West Lafayette, IN 47907
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