1. Eover for heavy atoms
In Lammps code, the calculation for the cases with atom mass > 21 g/mol has slightly different results from formulation given in ref [1].
𝐸 𝑜𝑣𝑒𝑟 = 𝑝 𝑜𝑣1 𝐷 𝑒 𝜎 𝐵𝑂 𝑖𝑗 ∆ 𝑖 𝑙𝑝𝑐𝑜𝑟𝑟 + 𝑉𝑎𝑙 𝑖 ∆ 𝑖 𝑙𝑝𝑐𝑜𝑟𝑟 exp⁡ 𝑝 𝑜𝑣2 ∆ 𝑖 𝑙𝑝𝑐𝑜𝑟𝑟
∆ 𝑖 𝑙𝑝𝑐𝑜𝑟𝑟 = ∆ 𝑖 − ∆ 𝑖 𝑙𝑝 1+ 𝑝 𝑜𝑣3 𝑒𝑥𝑝 𝑝 𝑜𝑣 ∆ 𝑗 − ∆ 𝑗 𝑙𝑝 𝐵𝑂 𝑖𝑗 𝜋 + 𝐵𝑂 𝑖𝑗 𝜋𝜋
This term becomes 0 for atom mass > 21 g/mol. I think this should be for atoms > 210 g/mol.
lib/reax/reax_poten.F line 1119
1. Mueller, J. E., et al . J. Phys. Chem. C. 4939–4949 (2010). - Formulation is from its supporting material.

2. W/ 21.0 g/mol exception, the shape of EOS can not be followed.
if (amas(ity1).gt.21.0)
if (amas(ity1).gt.210.0)
W/ 21.0 g/mol exception, the shape of EOS can not be followed.
The ignored term need to be included as you can see in the graph below.