could you please help me to define this lj potential in LAMMPS

This is the *same* LJ potential as LAMMPS uses, only that it uses the minimum of the potential instead of the zero crossing: R_0 = \sigma \cdot 2^{1/6}.

If I change this formula in the C++ file, it will work or not ?

I am attaching a C++ file screenshot

No c++ changes are needed.

Yours are incorrect, anyway.

@Sachin_varshney,

There are two ways to write the Lennard-Jones potential equation as pointed out by @akohlmey. The one you showed uses the distance of the energy minimum to the origin. The one used in LAMMPS doc uses the distance to the zero crossing to the origin. Both are **strictly equivalent** and the way to convert one parameter value to the other was already pointed out to you.

See, for example, here for more details.

Thank you, sir.

Thanks sir