III.G.1.a.

Comparison of levels of theory for S-S

Click on an entry for a histogram of the values.
The subscript refers to how many bonds of that type have been calculated.

average calculated bond lengths (Å)

Methods with predefined basis sets
semi-empirical	AM1	1.9210 7
	PM3	1.9326 21
	PM6	1.9744 25
composite	G2	1.9461 25
	G3	1.9460 25
	G3B3	2.0181 25
	CBS-Q	1.8858 16

average calculated bond lengths (Å)

Methods with standard basis sets
		STO-3G	3-21G	3-21G*	6-31G	6-31G*	6-31G**	6-31+G**	6-311G*	6-311G**	6-31G(2df,p)	6-311+G(3df,2p)	TZVP	cc-pVDZ	cc-pVTZ	cc-pVQZ	aug-cc-pVDZ	aug-cc-pVTZ	aug-cc-pVQZ	cc-pV(D+d)Z	cc-pV(T+d)Z	aug-cc-pV(T+d)Z	cc-pCVDZ	cc-pCVTZ	Sadlej_pVTZ
hartree fock	HF	2.0268 23	2.1853 25	1.9782 25	2.1452 25	1.9877 25	1.9877 25	1.9885 25	1.9943 25	2.0024 23	1.9857 23	1.9926 16	1.9994 25	2.0018 25	1.9819 25	1.8913 10	2.0010 25	1.9816 25	1.9075 7	1.9260 7	1.9690 19	1.8916 7	1.9431 4	1.9192 4	1.8992 1
hartree fock	ROHF		2.1519 4	1.9431 4	2.1578 2	1.9548 4	1.9548 4	1.9557 4	1.9606 4	2.0027 2			2.0062 2	1.9661 4	1.9458 4		2.0055 2	1.9848 2		1.9481 3	1.9759 2
density functional	LSDA	2.0451 25	2.1238 25	1.9877 25	2.1506 25	2.0023 25	2.0023 25	2.0012 25	2.0037 25	2.0038 25	1.9822 25		2.0266 2	2.0106 25	1.9861 25		2.0082 25	1.9490 5	2.0007 1	1.9244 4	1.8668 2	1.8645 2
	SVWN		2.1734 25			2.0123 22	2.0208 2	2.0010 25	2.0257 2	2.0257 2	1.9983 2			2.0297 2	2.0032 2		2.0248 2	2.0001 2		1.8777 2	1.8512 3	1.8645 2
	BLYP	2.0882 23	2.2356 25	2.0371 25	2.2059 25	2.0519 24	2.0519 24	2.0525 25	2.0590 25	2.0653 23	2.0021 14		2.0837 2	2.0604 25	2.0362 25		2.0882 14			1.9419 5	1.8842 3	1.8816 3
	B1B95	2.0464 23	2.1223 25	1.9838 25	2.1474 25	1.9948 25	1.9966 25	1.9959 25	2.0001 25	2.0065 23	1.9865 23		2.0158 2	2.0054 25	1.9825 25	1.8988 4	2.0021 25	1.9463 10	1.8976 4	1.9012 5	1.8977 7	1.8971 7	1.9627 4	1.9358 4
	B3LYP	2.0648 23	2.2039 25	2.0084 25	2.1743 25	2.0232 25	2.0232 25	2.0226 25	2.0275 25	1.9939 9	2.0085 22	2.0322 13	2.0282 25	2.0965 25	2.0088 25	1.9321 9	2.0293 25	1.9712 17	1.9324 7	1.9511 7	1.9920 21	1.9159 7	1.9867 4	1.9571 4	1.9415 1
	B3LYPultrafine					2.0232 25		1.9894 7
	B3PW91	2.0653 17	2.1913 24	1.9936 25	2.1555 23	2.0065 25	2.0066 25	2.0059 25	2.0096 25	1.9770 9	1.9612 14		2.0288 2	2.0155 25	1.9932 25		2.0430 14			1.9094 5	1.8564 3	1.8553 3
	mPW1PW91	2.0589 17	2.1799 25	1.9971 21	2.1497 25	2.0023 25	2.0001 25	1.9995 25	2.0033 25	2.0096 23	1.9553 15		2.0213 2	2.0089 25	1.9875 25		1.9899 8	1.9982 2		1.9050 5	1.8529 3	1.8519 3
	M06-2X	2.0315 2	2.1803 2	1.9950 2	2.1545 2	1.9985 25	2.0091 2	2.0085 2	2.0155 2	2.0155 2	1.9933 2			2.0177 2	1.9966 2		2.0147 2	1.9944 2		1.8606 3	1.8537 3	1.8527 3
	PBEPBE	2.0815 17	2.2869 17	1.9756 11	2.1413 11	1.9912 16	1.9914 16	1.9902 16	1.9939 16	2.0359 23	2.0117 23	2.0266 14	2.0518 2	2.0946 17	1.9767 16	1.9303 3	1.9957 5	2.0034 11	1.9283 3	1.9225 5	1.9216 7	1.9224 6	2.0088 3	1.9791 3	1.9220 1
	PBEPBEultrafine					2.0099 9
	HSEh1PBE	2.0416 2	2.1930 2	2.0007 2	2.1645 2	2.0074 23	2.0140 2	2.0135 2	2.0209 2	2.0209 2	1.9961 2		2.0218 2	2.0235 2	2.0008 2		2.0201 2	1.9985 2		1.9089 4	1.8531 3	1.8521 3
Moller Plesset perturbation	MP2FC	2.0728 17	2.2458 23	1.9888 25	2.2082 25	2.0025 25	2.0025 25	2.0020 25	2.0057 25	2.0106 23	1.9564 13		2.0115 25	2.0209 25	1.9872 23	1.9189 5	2.0237 25	1.9775 11	1.9159 3	1.9436 7	1.9767 21	1.9077 5	1.9843 4	1.9501 4	1.9570 1
	MP2FU	2.0724 17	2.2446 24	1.9970 21	2.2180 21	2.0009 25	2.0009 25	2.0006 25	1.9727 17	1.9754 9	1.9549 9		2.0183 2	2.0167 24	1.9930 22	1.9139 3	1.9707 10	1.9716 5	1.8411 1	1.9413 7	1.9702 21	1.8993 5	1.9825 4	1.9459 4
	ROMP2	2.0462 2	1.9938 2	1.9938 2	2.1614 2	2.0082 2	2.0082 2	2.0079 2	2.0155 2	2.0155 2	1.9942 2		2.0198 2	2.0248 2	1.9983 2		2.0279 2
	MP3					2.0055 25														1.9585 3	1.8871 2	1.8851 2
	MP4	2.1214 8	2.2631 21			2.0159 25			2.0140 2	1.9631 7					1.9669 10					1.9344 5	1.8762 3	1.8735 3
	B2PLYP	2.0540 2	2.2290 2	2.0128 2	2.1998 2	2.0140 25	2.0282 2	2.0136 25	2.0379 2	2.0379 2	2.0113 2		2.0392 2	2.0413 2	2.0163 2		2.0416 2	2.0147 2		1.9258 4	1.8662 3	1.8644 3
Configuration interaction	CID	2.1038 8	2.2186 20	1.9530 12	2.1470 12	1.9936 25	2.0535 1		1.9705 14					2.0749 1						1.8197 1	1.8054 1	1.8055 1
Configuration interaction	CISD	2.1039 8	2.2226 20	1.9464 11	2.1437 11	2.0564 25	2.0538 1		1.9600 11					2.0753 1						1.8218 1	1.8075 1	1.8075 1
Quadratic configuration interaction	QCISD	2.1214 10	2.2731 24	2.0062 21	2.2287 21	2.0729 25	2.0192 21	2.0072 24	2.0156 25	1.9979 13	1.9868 7		2.0332 2	1.9944 16	1.9728 13		2.0414 2	2.0068 2		1.9513 7	1.9328 9	1.8682 3
Quadratic configuration interaction	QCISD(T)					2.0153 24	1.9591 2	1.9593 2	1.9882 4	2.0909 2			2.0441 2	1.9925 7	1.9638 7		1.9961 7	1.9698 5		1.8525 1	1.8401 1	1.8404 1
Coupled Cluster	CCD	2.1198 10	2.2483 21	2.0017 21	2.2129 21	2.0053 25	2.0149 21	2.0147 21	2.0177 23	1.9982 7	1.9823 7		2.0228 2	1.9882 16	1.9699 9		1.9817 5	1.9504 5		1.9464 7	1.9103 8	1.8827 6	1.9425 2	1.9074 2
	CCSD		2.1739 2			1.9707 16	1.9386 2	1.9384 2	1.9713 4	2.0831 2				1.9947 4	1.9653 4					1.8365 1		1.8226 1
	CCSD(T)		2.1892 3			2.0203 22	1.9647 6	1.9465 3	1.9865 4	2.0352 3		1.9040 1	2.0420 2	1.9859 11	1.9573 13	1.9170 1	1.9893 11	1.9687 6		1.9526 3	1.9353 5	1.9430 4	1.9945 4	1.9597 4
	CCSD(T)=FULL					1.9785 9							2.0416 2	2.0343 4	2.0028 4	1.9139 1	2.0412 4	1.9996 4		1.9473 5	1.9174 7	1.9401 5	1.9921 4	1.9560 4

average calculated bond lengths (Å)

Methods with effective core potentials (select basis sets)
		CEP-31G	CEP-31G*	CEP-121G	CEP-121G*	LANL2DZ	SDD
hartree fock	HF	2.1426 25	2.0018 25	2.1434 25	2.0003 25	2.1706 24	2.1721 24
density functional	B1B95	2.1924 18	2.0465 18	2.2355 2	2.0865 2	2.2615 2	2.2448 2
density functional	B3LYP	2.1860 25	2.0392 25	2.1837 25	2.0363 25	2.2144 24	2.1997 25
Moller Plesset perturbation	MP2FC	2.2090 25	2.0215 25	2.2078 25	2.0176 25	2.2345 24	2.2315 24

For descriptions of the methods (AM1, HF, MP2, ...) and basis sets (3-21G, 3-21G*, 6-31G, ...) see the glossary in section I.C. Predefined means the basis set used is determined by the method.