Why is the BMH potential function expressed in the literature in this form
while in the lammps handbook it does look like this
If I want to use the first form, how do I write the pair-style command？
Any help would be greatly appreciated.
It is not just the LAMMPS manual. It is elsewhere, too (e.g. Born-Huggins-Meyer potential page on SklogWiki - a wiki for statistical mechanics and thermodynamics), and I suspect that the literature you are quoting is the outlier and it is - as far as I can tell - a different potential.
Presumably you can run this in LAMMPS by writing each pair coeff as:
\rho = 1/\alpha
A = b(1+z_i/n_i + z_j/n_j)
\sigma = \sigma_i + \sigma_j
C = D = 0
Thank you for your answer, it will help me very much!
I understand and thank you very much for your help！