Table 2.

Atomic polarizabilities (au) determined by GA (Wang et al 2009) optimization to reproduce experimental molecular polarizabilities for a set of 420 molecules (Bosque and Sales 2002). Four different polarizability models: Applequist, Thole-linear, Thole-exponential and Thole-exponential used in the Tinker program, have been employed. Optimization was performed for the fully interactive model and the model in which induced dipole interactions 1–2 and 1–3 were screened; 1–4 interactions were scaled down by 1.2, as with regular 1–4 electrostatic interactions in the AMBER force field. AUE—average unsigned error, RMSE—root mean square error, APE—average per cent error.

(a)
	Applequist	Thole-lin.	Thole-exp	Thole–Tinker
C1	2.83	11.32	9.22	12.03	sp1
C2	4.31	11.49	10.55	12.04	sp2
C3	4.77	7.74	8.25	6.39	sp3
H	1.49	3.97	3.24	4.47
NO	5.07	14.95	13.16	16.54	N in nitro
N	3.38	8.56	7.83	8.32	Other N
O2	2.26	4.33	3.81	3.44	sp2
O3	2.60	4.60	4.28	4.17	sp3
F	3.07	4.11	3.22	4.11
Cl	13.78	16.78	16.89	16.86
Br	21.01	24.07	24.58	23.75
I	33.03	37.39	38.67	37.18
S4	11.33	20.64	19.40	20.10	S—sulfones
S	14.78	24.49	23.73	23.77	Other S
P	6.26	15.31	13.39	14.42
a	—	2.06	2.01	0.38	Screen. length
AUE	3.01	1.31	1.12	1.32
RMSE	4.55	1.89	1.69	1.92
APE (%)	3.82	1.55	1.30	1.58

(b)
	No 1–2, 1–3 dipole interactions 1–4 interactions scaled down by 1.2
	Applequist	Thole-lin	Thole-exp	Thole–Tinker
C1	9.65	9.65	9.55	9.66	sp1
C2	8.76	8.72	8.61	8.71	sp2
C3	6.21	6.12	5.77	6.06	sp3
H	2.99	3.03	3.19	3.06
NO	10.11	10.06	9.94	10.12	N in nitro
N	6.30	6.26	6.09	6.24	Other N
O2	4.00	4.01	4.04	3.99	sp2
O3	4.09	4.07	3.97	4.08	sp3
F	3.36	3.40	3.55	3.43
Cl	16.03	16.04	16.11	16.05
Br	23.65	23.66	23.72	23.67
I	37.65	37.63	37.57	37.64
S4	15.89	15.87	15.99	15.97	S—sulfones
S	21.48	21.46	21.36	21.44	Other S
P	12.33	12.27	12.23	12.25
a	—	2.39	2.11	0.79	Screen. length
AUE	0.98	0.98	1.02	0.99
RMSE	1.53	1.54	1.57	1.54
APE (%)	1.17	1.17	1.22	1.18