eigenstateOccupationParameters

	Core NanoLanguage elements
calculateTotalEnergy	electronDensityParameters

Name

eigenstateOccupationParameters — Controls the occupation of Kohn-Sham orbitals using a Fermi distribution.

Synopsis

Namespace: ATK.KohnSham or ATK.TwoProbe

dictionary eigenstateOccupationParameters(temperature)

Description

A function that returns a dictionary with the parameters that are used to determine the occupation of the Kohn-Sham orbitals when calculating the electron density.

List of arguments

temperature

The electron temperature $T$ that enters in the Fermi distribution

$\displaystyle f(E) = \frac{1}{\exp((E-E_\mathrm{f})/k_\mathrm{B}\cdot T) +1}$

where $E_\mathrm{f}$ is the Fermi energy, and $k_\mathrm{B}$ is the Boltzmann constant.

Default: 300*Kelvin

Usage examples

from ATK.TwoProbe import *

eigenstate_occupation_parameters = eigenstateOccupationParameters(
    temperature = 1160*Kelvin
    )

Notes

For molecules with a very small HOMO-LUMO gap, the convergence rate of the self-consistent loop can usually be improved by increasing the electron temperature to smooth the Fermi distribution. Also metals (and in particular semi-metals) can sometimes be hard to converge at a low electron temperature, if there are band edges close to the Fermi level. In such cases, it is often possible to use a smaller k-point sampling if the the electron temperature is increased.

The electron temperature has nothing to do with the lattice temperature or phonons, but is strictly related to the electron distribution function.


calculateTotalEnergy		electronDensityParameters