Please use 4.1.5, it has checks for these kinds of things.

Probably what you are seeing is that the charge is leaking out of the
device region during your SCF. This is an indication of one or a
combination of the following:
- your initial Hamiltonian is far from the open-boundary one. I.e. your
electrode regions are too close to the scattering in the device
- your mixing weight is too high
- your convergence parameters too loose during the Siesta SCF
- your integration variables in TranSiesta could be better (more points)
- you started a biased calculation (V) from a previous TranSiesta
calculation (V'), and the difference V - V' is too large for the system to
converge properly, try a smaller dV

There may be other things as well. Also, I hope you are doing a 0 V
calculation to start with.

Den fre. 12. nov. 2021 kl. 22.08 skrev Neculai PLUGARU <>:

> Dear SIESTA community
> I attempt to perform conductance calculations on a heterostructure with
> two interfaces, (slab geometry) which was previously relaxed and then
> the SCF calculation produced correct results.
> I use SIESTA v4.1-b4, Compiler version: ifort (IFORT) 18.0.5 20180823,
> PARALLEL version.
> However, although the SIESTA cycle in the transport calculation
> converges and the Harris, KS and Free energies are negative, TS starts
> from (huge) positive energy values, then the calculation converges
> according to the DM tolerance criterion, the energies are still
> positive, the forces on atoms are huge and the populations on orbitals
> are wrong. The leads are cut from the electrodes, so that the scattering
> region comprises the interfaces and the leads still are about one
> nanometer long each.
> I would greatly appreciate your comments to solve this issue.
> Thank you,
> Neculai
> *******************************************************
> N. Plugaru
> National Institute for R&D in Microtechnologies (IMT-Bucharest)
> Simulation, Modelling and Computer-Aided Design - Laboratory L5
> 126A, Erou Iancu Nicolae Street, 077190, Ilfov
> Bucharest, ROMANIA
> E-mail:
> Tel:  +4021 269 0777
> *******************************************************
> --
> SIESTA is supported by the Spanish Research Agency (AEI) and by the
> European H2020 MaX Centre of Excellence (

Kind regards Nick
SIESTA is supported by the Spanish Research Agency (AEI) and by the European 
H2020 MaX Centre of Excellence (

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