$$E_{bond} = D_e\left[1 - e^{-a(r-r_0)}\right]^2$$
Morse potential: \(D_e\) is the bond dissociation energy, \(r_0\) is the equilibrium bond length
$$E_{total} = \sum E_{bond} + \sum E_{angle} + \sum E_{torsion} + \sum E_{vdW}$$
Molecular force field (MMFF/UFF): the sum of bond, angle, dihedral, and van der Waals potentials
$$\text{IHD} = \frac{2C + 2 + N - H - X}{2}$$
Index of hydrogen deficiency (IHD): \(C, N, H, X\) are the atom counts of each element. Each ring or double bond adds +1