There is no information for your inquiry. I've checked the official website and available documents, but there is nowhere specified or even mentioned about the dispersion of gas. If you have the software installed, then access the Help section and read through the documentation. It's the best thing to do since I the software supports dispersion modeling, but it's not detailed in a simple way to understand.
You can also get in touch with the developers using Help > About where the contact details are located in most of the cases.