Request on fix ttm

Am running an MD simulation of fs laser ablation of Ti. I have looked at various literature but can not figure out how and where to apply 0.9J/cm2 of laser to my system using the fix ttm.
I would very much appreciate if you can help me out. A code will be an added advantage. Thanks in advanced.
Best regards

Fix ttm applies energy to an electronic subsystem volumetrically. The fluid-like electronic subsystem is coupled to your atomic subsystem that you model with MD. You'll have to figure out how to model your surface-area-applied laser energy in a volumetric way that makes sense and is a reasonable model. The fix ttm code has been supplied with LAMMPS, but you'll have to search the literature for help on specific modeling questions like this.