[Smeagol-discuss] failed diagonalisation (leading minor of order 45 of B is not positive definite)

[Zeila Zanolli]

Dear Smeagolers,

I was trying to run 'leads'-like calculations for a piece of graphene but
I've got the following warning and error:

  xijorb: WARNING: orbital pair      1   537 is multiply connected

  *Maximum dynamic memory allocated =   602 MB
  The leading minor of order           45  of B is not positive definite.
  The factorization of B could not be completed
  and no eigenvalues or eigenvectors were computed.
  Terminating due to failed diagonalisation
  Stopping Program


Now, since this diagonalisation is the same as in siesta, i've also tried
to make a normal siesta2.0 calculation with the same input and i had
(withour big surprise) a

  Failure to converge standard eigenproblem

error. I have posted this problem on the siesta mailing list as well, but
i haven't got any answer yet.
Note that I've tried both DivideAndConquer true and false, but neither
option works.

Note also that there is no error if i'm using a SZ basis (default
EnergyShift and SplitNorm), but the error is there for a DZ and DZP basis
(default EnergyShift and SplitNorm).

As further weird thing, when I did the 'lead' calculation with 1x1x30
k-mesh there was no error, so - i've thought - the input coordinates
should be ok.
Then I've did the same 1x1x30 with siesta2.0, and the code crashed with
the 'failure to converge'error as before.

Another thing that I didn't get is that for a similar input structure (a
graphene stripe along the x direction) the lead calculation succeeded
(from  a k-mesh greather or equal to 48x1x100, but crashed for smaller
k-meshes).
In addition, as a test, i did a siesta calculation for the 48x1x100 mesh,
and that crashed!

So... can anyone help in understanding what is going on?

I'm attaching here .fdf, .out and note that i'm reading the coordinates
from the .XV file.

nb: I'm using intel LAPACK




----------------------------------------------------------------------
Dr. Zeila Zanolli

Université Catholique de Louvain (UCL)
Unité Physico-Chimie et de Physique des Matériaux (PCPM)
Place Croix du Sud, 1 (Boltzmann)
B-1348 Louvain-la-Neuve, Belgium
Phone: +32 (0)10 47 2617
Mobile: +32 (0)487 556699
Fax: +32 (0)10 47 3452
e-mail: zeila.zanolli at uclouvain.be
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