Table 2. Values of the Structural Parameters Obtained from the NIXSW Data (Table 1) and from the SXRD Data Analysis for the Two Alternative Structural Models^a.

	NIXSW	SXRD – adatom	SXRD– no-adatom
F4TCNQ height	3.08 ± 0.07 Å	3.22 ± 0.09 Å	3.13 ± 0.10 Å
adatom height		2.69 ± 0.10 Å
rumpling amplitude 1st layer		0.53 ± 0.20 Å	0.56 ± 0.20 Å
rumpling amplitude 2nd layer		0.14 ± 0.20 Å	0.16 ± 0.20 Å

^aThe height of the F₄TCNQ given here corresponds to the height of the quinone ring of CF carbon atoms. NIXSW distinguishes these C atoms from other atoms in the molecule, but the SXRD calculations are of a molecule of a fixed conformation, varying the positions relative to the underlying substrate, so while the quoted precision of the NIXSW value is of the height of this particular part of the molecule, whereas the SXRD precision value is of the height of the whole (rigid) molecule. The SXRD precision estimates for the molecule and adatom heights are determined by the range of individual parameter values that lead to a value of χ² within 5% of the best-fit value.¹⁹ In each case, the height is given relative to a bulk-terminated outermost Ag(111) layer, thereby taking account of the small (0.03 Å) change in outermost layer spacing found in the SXRD analysis. Rumpling amplitudes correspond to the height differences of the lowest and highest Ag atoms within each layer.