I have a problem to describe a potential for the bond stretches in LAMMPS. This potential includes two terms. The first term is Morse potential, the second term is -D. That means, V=morse potential-D, where, D is the coefficient in the Morse potential. For first term, I can use the command "bond_style morse". For the second term, I don't know how to describe it in LAMMPS. Does anyone know there are some commands which could be used to describe both Morse potential and "-D" term together? If not, Should I modify the source code of Morse potential to get this bond stretch potential? Your any suggestions would be greatly appreciated.
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