# Strong-weak partitioning¶

The transition lines (.trans) can be partitioned into strong/weak using an absorption intensity threshold for a reference temperature. This option is invoked by a combination of two keywords: TRANS as a type of profile (stand-along keyword) and cutoff exp (also stand-along keyword). The reference temperature is defined using Temperature. The dynamic partitioning cutoff is given by

$$I_{\rm cut} = I_0 \exp(-\nu/\alpha)$$

The format of the cutoff line is as follows

cutoff exp 1e-25  alpha  2000


where $$I_0=1e-25$$ and $$\alpha=2000$$.

For example:

Temperature  3000.0
Range 0.0  10000.0

absorption

cutoff Exp 1e-25  alpha  2000

trans

output part

States       H2O.states
Transitions  H2O.trans


This input will creates two files H2O.trans.part.w and H2O.trans.part.s, with the weak and strong lines in the standard .trans format. In case of multiple .trans files in Transitions section, each of .trans generates two .w and .s files.