[DFTB-Plus-User] calculation of the onsite energy and the hopping parameter in a molecule

[Jacek Jakowski]

Nadia,

something is wrong with your overlap matrix  S.   This matrix should be
positive definite, otherwise  the diagonalizaiton will fail with error
"cholesky decomposition problem".    Complex numbers in S^(-1/2) suggest
that  some eigenvalues  of S   negative and that S in NOT  positive
definite.

Thanks,

Jacek


On Thu, May 1, 2014 at 10:36 AM, <n.salami at srbiau.ac.ir> wrote:

> Dear dftb+ users,
>
> Good time,
>
> I need the hopping parameter and the onsite energy in the orthogonal basis
> set for a molecule in the tight binding method.
> I have done the dftb calculation. So I have the elements of the overlap
> and Hamiltonian matrix in non orthogonal basis set. I have calculated
> S^(-1/2) to do the lowdin transformation. But its elements are complex
> numbers.
>
> Thanks a lot in advance for your comment.
>
> Kind Regards.
> Nadia
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