  Electron emission from nanometric size emitters becomes of increasing
interest due to its involvement to sharp electron sources, vacuum breakdown
phenomena and various other vacuum nanoelectronics applications. The most
commonly used theoretical tools for the calculation of electron emission are
still nowadays the Fowler-Nordheim and the Richardson-Laue-Dushman equations
although it has been shown since the 1990's that they are inadequate for
nanometrically sharp emitters or in the intermediate thermal-field regime. In
this paper we develop a computational method for the calculation of emission
currents and Nottingham heat, which automatically distinguishes among different
emission regimes, and implements the appropriate calculation method for each.
Our method covers all electron emission regimes (thermal, field and
intermediate), aiming to maximize the calculation accuracy while minimizing the
computational time. As an example, we implemented it in atomistic simulations
of the thermal evolution of Cu nanotips under strong electric fields and found
that the predicted behaviour of such nanotips by the developed technique
differs significantly from estimations obtained based on the Fowler-Nordheim
equation. Finally, we show that our tool can be also successfully applied in
the analysis of experimental I-V data.
