I have a forcefield with O,H,Ca,Si,C but the problem is that the forcefield does not include interaction between Ca and C. I checked the force field databases and didn’t see any forcefields that fit my criteria. So Can I take a parameter from another forcefield that include interaction between Ca and C and add it to the existing forcefield
ReaxFF force fields are parameterized for specific use cases. Only looking at the elements that your system has is not sufficient. Augmenting one ReaxFF force field file with parameters from a different file is a bad idea. You are effectively creating a “zombie” and there is no way to predict whether you will get meaningful results. Most likely not.