[DFTB-Plus-User] : Simulating Silicon Crystal : Does DFTB estimate the phase of the wavefunction accurately?

[Bálint Aradi]

Dear Fahd,

> (data from wp-1-184-5-real.cube) + 1i* (data from wp-1-184-5-imag.cube).
> 
> Is the above combination a correct way for estimating the wave function,
> and will the relative phase between real and imaginary parts be treated
> correctly at all coordinates in space? 

Yes, the real and imaginary cube files are built using the real and
imaginary part of the complex eigenvectors, respectively. The way you
combine them seems to be correct and you should get back the correct
complex wave function everywhere. (Unless we have a bug in waveplot.)

> I have also tried playing with different unit cells (primitive and
> cubic) for silicon in DFTB. /The results from different unit cells give
> me the same charge densities, but the Fourier transforms of the wave
> functions are different. /Hence, I was wondering whether I am combining
> the wave functions correctly, and does DFTB take into account the phase
> of the wave function accurately. 

Yes, I am pretty sure, DFTB+ takes the phase of the wave-function
correctly into account.

Just to make a check, you may consider to calculate a single atomic
hydrogen chain (orthogonal supercell with two supercell vectors set to
large values). That you could compare to results obtained by other means
(e.g. either VASP calculation or even analytic ones) and spot, if there
are any bugs.

  Best regards,

  Bálint

-- 
Dr. Bálint Aradi
Bremen Center for Computational Materials Science, University of Bremen
http://www.bccms.uni-bremen.de/cms/people/b-aradi/


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