### Occupation calculation

It calculates the equilibrium properties of the device considering the calculated band structure.

In the main window the following parameters can be set:

- The following parameters set the convergence parameters of the nonlinear poisson equation, and for the charge neutrality calculation.

*It can be selected whether polarization charge calculation is necessary, and inclusion to the poisson equation. Also the classical spectrum can be calculated, which treats the device as a bulk semiconductor.

*The different quantum mechanical models can be set to the envelope function calculation. It can be chosen that dispersion is considered or not, or should it be calculated for charge density calculation, or self consistent calculation, or optical properties calculation.

*The Quantu mechanical optical spectrum of the device can be calculated enabling the following parameters. The interaction energy calculates the Coulomb interaction energy between charge carrier states.

#### Thermal equilibrium

It calculates the temperature distribution in the device with a linear static model. More info.

#### Charge models

The distribution of charge carriers in semiconductors is influenced by the band structure of the sample and outer effects, like temperature inhomogenity, and the applied voltage. According to an assumption, which states, that the charge density of a carrier is defined by the local physical quantities. ($E_f$ fermi energy, $U$ potential, $T$ temperature, $E_{bands}$ conduction and valence band energies) \[ n(r_0) = n(E_f(r_0), U(r_0), T(r_0), E_{bands}(r_0)) \]

The carrier density distribution should also should fulfill the Poisson equation in position space. From the equation above, if the $n(U), p(U) $dependence is known the charge distribution can be calculated in the sample. More on

#### Dopig

Different impurities can be defined for the structure for each simulation domains. Acceptors, Donors, with different concentration profiles, and degeneracy and energy levels.

#### Electrostatics

It defines the boundary conditions for the Poisson equation. If charge neutral condition is specified, then during the calculation step it tries to find the neutral device potential with sifting these define potential values with a constant value. If no boundary condition is defined then it calculates like it first grid point is set to charge neutral. (Except for Device calculation, because when a contact is defined it tries to find the charge neutral contact.)

#### Quantum mechanics

Sets the boundary condition of the Quantum mechanical envelope function calculation. Can be ignored if we calculate classically óor a Neumann boundary condition is enough.