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The values of D in the LAMMPS file SiC.vashishta and the original paper that it is based on are indeed different, but neither is wrong. The different values of D are due to differences in units and also in the energy formulae. Assuming that the LAMMPS file can be used in LAMMPS to reproduce the results in the paper (no guarantee there, since it is not part of our regression testing, but probably true, and you can verify for yourself), it is safe to assume that someone (me) carefully converted the value from the paper into the correct value for LAMMPS. I could certainly reproduce that calculation for you here, but I think it is better, for me and for you, if you do it yourself. In order to figurre out how to do this, you will have to carefully read the paper and the LAMMPS documentation for pair style vashishta. Note also that the LAMMPS file helpfully contains the key information:
D = eV*Angstroms^4
Note: Value of D here equals D/2 in paper
If you suspect that the LAMMPS value of D is actually wrong, as opposed to different, please let us know.