[DFTB-Plus-User] point charges

[Bhatt, Mahesh]

Dear Dr. Blint,

Thank you for your kind suggestion.

I found the problem is k-point and now, I am using gamma k-point according your suggestion and now SCC convergence got for even high charges.

Sincerely
Mahesh
________________________________________
From: dftb-plus-user-bounces at dftb-plus.info [dftb-plus-user-bounces at dftb-plus.info] on behalf of Bálint Aradi [balint.aradi at bccms.uni-bremen.de]
Sent: Monday, May 27, 2013 7:49 AM
To: User list for DFTB+ related questions
Subject: Re: [DFTB-Plus-User] point charges

Hi,

>
> The modified point charges are:
>
> ElectricField = {
> PointCharges = {
> CoordsAndCharges = {
> 3.3   -1.2   0.9   9.2
> 5.2   -3.4   5.6   -3.3
> }
> }
> }
>
> Now, the point charges look like far from H atom. Please let me know the cause for still SCC unconvergence.

Still, your unshielded charges are **huge**. Setting them to 0.1 and
-0.1 makes things converge.

Also note, that setting a k-point-sampling

1 0 0
0 1 0
0 0 1
0.1 0.1 0.1

is somewhat strange. You wouldn't obtain much better quality than pure
Gamma point sampling, but it would take longer (using complex numbers
instead of real ones for the diagonalization) and the symmetry of your
forces would be eventually incorrect.

  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/