For high fields which are parallel to the current flow, the effects of velocity saturation must be taken into account. A general approach is to multiply the low-field mobility (e.g., Arora and/or Lombardi model) by a reduction factor which takes into the consideration the high longitudinal (parallel) fields:
for which 
is the low field mobility, and 
is
the high field longitudinal reduction factor. The form of
used for silicon is:
The temperature dependence of 
is given by:
Table 2 summarizes the Prophet parameter names and default values for the longitudinal mobility reduction model.
Table 2: Longitudinal Field Mobility Reduction Model Parameters and
Default Values