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| - | ===== nextnano.QCL - Software documentation ===== | + | ===== nextnano.QCL - General remarks ===== |
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| - | ===== General remarks ===== | + | |
| nextnano.QCL is a console application that is run from within the [[http://www.nextnano.com/products/nextnanomat.php|nextnanomat]] software (GUI). Alternatively, it can be executed from the command line. The input file specifies the device that shall be simulated. | nextnano.QCL is a console application that is run from within the [[http://www.nextnano.com/products/nextnanomat.php|nextnanomat]] software (GUI). Alternatively, it can be executed from the command line. The input file specifies the device that shall be simulated. | ||
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| If you have further questions, see the [[qcl:faq|FAQ]] or contact <support@nextnano.com>. | If you have further questions, see the [[qcl:faq|FAQ]] or contact <support@nextnano.com>. | ||
| - | ===== Working principle ===== | ||
| - | |||
| - | The code uses **field-periodic boundary condition**. | ||
| - | In this way the simulation accounts for an infinite periodic structure, with a periodic electric field. | ||
| - | Coherent transport between periods is accounted on a length set by ''<Coherence_length_in_Periods>''. | ||
| - | |||
| - | The results of the calculation should not depend on which material layer the sequence starts, i.e. a cyclic permutation in the material layer sequence should not change the simulation results. | ||
| - | |||
| - | === Program flow === | ||
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| - | {{ :qcl:flowchart.jpg?400 |}} | ||
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| - | In the beginning of the calculation, the single-band effective mass Schrödinger equation is solved in real space. | ||
| - | The calculated energy levels and wave functions are then used as input to the NEGF algorithm. | ||
| - | The wave functions are termed **modes** and the NEGF algorithm is written in terms of **mode space** and not **real space** to make it computationally more efficient. | ||
| - | The number of QCL periods that are input to this Schrödinger equation are specified in ''<Number_of_lateral_periods_for_band_structure>''. | ||
| - | In general, the core of the NEGF algorithm should be rather independent of this number, e.g. | ||
| - | <code> | ||
| - | <Number_of_lateral_periods_for_band_structure> 4 | ||
| - | </Number_of_lateral_periods_for_band_structure> | ||
| - | </code> | ||
| - | should lead to very similar results compared to a value of ''5'' but the numerical values might differ slightly. | ||
| - | {{ :qcl:ldos_emin_emax_okay.jpg?200 |}} | ||
qcl/software_documentation.1489594147.txt.gz · Last modified: 2017/03/15 16:09 by thomas.grange
