$negfoverlapcalculation

$negfoverlapcalculation is the command to setup the region of surface roughness. The first term is to setup what kind of structure, 1 is circle, and 2 is rectangular for cross section region. If the first term is 1, then the four parameters after that are fix factor for surface roughness scattering, root mean square height$\Delta$of surface roughness, diameter of the outer circle, and the diameter of the inner circle. If the first term is 2, then the four parameters after that are fix factor for surface roughness scattering, root mean square height$\Delta$of surface roughness, width, and height.
Example:

$negfoverlapcalculation
1
1.0e-3 1.0e-7 20.0e-7 16.0e-7
387 396
# Note: 1 --> circle, 2 --> rectangular
# sfix rms_h t_diameter in_diameter (unit: cm) for circle
# sfix rms_h width height (unit: cm) for rectangular
# loadoverlapstart loadoverlapend

The last two parameters is what region of overlap. For example in this case we have 681 mesh grids from drain(left) to source(right), and the position of channel is from 300 to 400, then 387 to 396 is in the channel near the source what region of overlap we choose.