Table 8.

Fit Parameters for the Calculation of ⁵⁷Fe Isomer Shifts^a

Functional	Fit Type	Method to calculate ρ(0)b	α	C	A	r2	MAE (mm s−1)
OLYP	Fe–S	S	−0.465	0.652	11820	0.88	0.031
		N	−0.463	0.413	11877
	Fe–NO	S	−0.295	0.572	11820	0.98	0.024
		N	−0.294	0.421	11877
OPBE	Fe–S	S	−0.461	0.670	11820	0.83	0.037
		N	−0.459	0.433	11877
	Fe–NO	S	−0.263	0.577	11820	0.98	0.020
		N	−0.262	0.442	11877
PW91	Fe–S	S	−0.485	0.787	11827	0.84	0.041
		N	−0.482	0.564	11884
	Fe–NO	S	−0.329	0.722	11827	0.98	0.027
		N	−0.328	0.570	11884
BP86	Fe–S	S	−0.495	1.012	11832	0.86	0.038
		N	−0.492	0.800	11889
	Fe–NO	S	−0.343	0.871	11832	0.98	0.027
		N	−0.342	0.725	11889
B3LYP	Fe–S	S	−0.279	0.651	11823	0.80	0.045
		N	−0.278	0.513	11880
	Fe–NO	S	−0.503	0.642	11823	0.91	0.050
		N	−0.501	0.393	11880
B3LYP//OLYP	Fe–S	S	−0.372	0.737	11823	0.92	0.028
		N	−0.370	0.553	11880
	Fe–NO	S	−0.314	0.685	11823	0.97	0.030
		N	−0.313	0.529	11880
B3LYP*	Fe–S	S	−0.346	0.620	11820	0.90	0.034
		N	−0.344	0.787	11876
	Fe–NO	S	−0.441	0.577	11820	0.96	0.033
		N	−0.439	0.791	11876
B3LYP*//OLYP	Fe–S	S	−0.407	0.668	11820	0.92	0.027
		N	−0.405	0.864	11876
	Fe–NO	S	−0.316	0.618	11820	0.97	0.028
		N	−0.315	0.771	11876
B3LYPc	Fe–S	N	−0.285	0.641	11816	0.82	0.044
	Fe–NO		−0.476	0.614		0.93	0.048
B3LYP*c	Fe–S	N	−0.326	0.529	11815	0.84	0.037
	Fe–NO		−0.435	0.428		0.93	0.045

^aUsing COSMO in combination with a STO-TZP basis set unless otherwise indicated.

^bThe ‘S’ serves to indicate that the Fe electron density has been calculated on a small sphere around the center of the Fe nucleus, while the ‘N’ indicates the density has been calculated at the Fe nucleus.

^cUsing COSMO in combination with the CP(PPP) basis set for Fe and the TZVP basis set for the remaining elements.