With regard to astrophysical applications it is convenient to calculate
the effective collision strength 
which is the thermal
average of the collision strength 
where 
. E denotes the kinetic energy of the outgoing
electron, T the electron temperature in Kelvin and 
, the Boltzmann constant. 
enters into the
excitation rate coefficient from level i to j through
where 
is the statistical weight of level i and
the energy difference between levels i and j in Ryd.
The de-excitation rate coefficient is given by
In Table 5 (click here) we have tabulated 
for all transitions within
the ground
configurations of KrIII, IV, V and temperatures ranging from
2000 to 50000 K. This temperature grid is especially suitable for the
modelling of gaseous nebulae and stellar atmospheres.