Table 3:

Abbreviations and associated forms of the alchemical transformation pathways. Indicated are the form of the dependent weight functions (in terms of smoothstep function SX, where X indicates the order of the smoothstep function); and n, m , α and β parameters of eqs 18 and 19 or n, m, α^LJ and α^Coul parameters of eqs 20 and 21. All α parameters are unitless, whereas the β parameter has units of Ų. The S2*[2,2,0.5,1] softcore potential differs in functional form from the others, using Eqns 20/21 for the separation-shifted scaling of the effective interaction distance with unitless α^LJ and α^Coul parameters rather than the more conventional form shown in eqs 18 and 19.

Abbreviation	W(λ)	n	m	α/αLJ	β/αCoul	Eqns.	Ref.	Comment
S0 Linear	S0	-	-	-	-	-	-	Linear mixing/no softcore
S0[6, 2, 0.5, 12]	S0	6	2	0.5	12	18/19	24	Default in AMBER18
S0[6, 2, 0.2, 17.3]	S0	6	2	0.2	17.3	18/19	57	Modified for improved stability
S2[6, 2, 0.2, 50]	S2	6	2	0.2	50	18/19	41	Default in AMBER20
S2*[2, 2, 0.5, 1]	S2	2	2	0.5	1.0	20/21	-	Present work, new form