Many of the carbon allotropes can serve as functional materials, which means it is highly desirable to have an accurate and efficient force field (FF) that can simulate and investigate the formation and conversion of those allotropes. Although such a system is made of only carbon atoms, we consider it as a multiple reaction system because it involves bond breaking and formation processes of many different types. An early example was given by Khaliullin et al. in 2010 , in which they built a NNP initially trained on zero temperature and randomly distorted structures of cubic and hexagonal diamond, hexagonal and rhombohedral graphite in the pressure range from -10 to 200