Error Messages

Quantum-Current-Poisson fails to converge

Most often Quantum-Current-Poisson calculation fails to converge because:

  1. The maximum number of iterations has been chosen too small (run{ } ==> outer_iteration{} ==> iterations) and the calculation just needs some more iterations.

  2. The number of electron or hole eigenstates has been chosen too small (e.g. quantum{ } ==> region{} ==> Gamma{} ==> num_ev).

    Check the occupations in the files wf_spectrum_"name quantum region"_"name quantum model".dat. If the occupation does not drop from the ground state to the highest excited state by several orders of magnitude, you need to calculate more states (= more possibilities to fill in charges).

  3. The under-relaxation parameter has been chosen too large (run{ } ==> outer_iteration{} ==> alpha_current).

    Check whether the solution oscillates (residuals do not drop continuously but increase in some iterations). Try to decrease the under-relaxation parameter in order to damp the oscillations.

  4. The minimum charge density in the current equation has been chosen too small (currents{ } ==> minimum_density).

    Try to increase the minimum charge density to improve conditioning of the current equation. In fact, the current equation is solved with the charge density = max( real density, minimum_density).

Error: (nodes number of coordinate 1) != (lines number in file)

Simulation *.log file contains the following error

error:(nodes number of coordinate 1) != (lines number in file)

It means that you have defined values at some grid points twice inside the imported file. Check if some points are duplicated in the file that you are trying to import. For example, you should avoid situation as the following:

…
1.0    0.5
1.1    0.5
1.2    0.5
1.2    0.6
1.3    0.6
…

In this case the point 1.2 is defined twice, which is the source of the problem.

nextnano++ exit code: -1073741795

Simulation *.log file contains the following exit code -1073741795 or other big negative number

(nextnano++ exit code: -1073741795)

Most likely you need to install the Microsoft Visual C++ Redistributable . Choose the corresponding version matching your operation system architecture (most likely X64) from the section Latest Microsoft Visual C++ Redistributable Version. It’s a typical error when running nextnano++ on Windows Server OS.

It is also possible that your CPU is not suited for nextnano++ executable, i.e., you are using processor from Pentium family, typical on old laptops. You can use nextnano++_Microsoft_32bit_serial.exe, see Error: The specified executable is not a valid application for this OS platform.

nextnano++ exit code: -1

Simulation *.log file contains the following exit code -1

(nextnano++ exit code: -1)

It means that the simulation has been aborted by nextnanomat or by other means.

nextnano++ exit code: 1

Simulation *.log file contains the following exit code 1

(nextnano++ exit code: 1)

It means that there is error in the command line calling the solver.

nextnano++ exit code: 3

Simulation *.log file contains the following exit code 3

(nextnano++ exit code: 3)

There is a problem with validating your license.

Last update: 25/10/2024