. 2014 Jun 12;4:5271. doi: 10.1038/srep05271

Table 2. Fitting parameters, ε, σ, and c of the modified Lennard–Jones composite potential, U_sh, U_sf and U_ih, as well as the corresponding non-linear spring stiffness per unit area, K.

Configuration	ε (kJmol⁻¹Å⁻²)	σ (Å)	c	Κ (kJmol⁻¹Å⁻⁴)	Κ (GPa/nm)
s-PMMA horizontal	0.25	2.96	0.67	0.66	11.0
s-PMMA face-down	0.30	2.75	0.71	1.04	17.3
i-PMMA horizontal	0.34	2.76	0.72	1.22	20.3

Table 2. Fitting parameters, ε, σ, and c of the modified Lennard–Jones composite potential, Ush, Usf and Uih, as well as the corresponding non-linear spring stiffness per unit area, K.