III.G.1.a.

Comparison of levels of theory for H-H

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	1.1305 19
	PM3	1.3618 45
	PM6	1.2513 50
composite	G2	1.2091 43
	G3	1.1658 40
	G3B3	1.3339 48
	CBS-Q	1.3371 37

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)	6-311+G(3df,2pd)	TZVP	cc-pVDZ	cc-pVTZ	cc-pVQZ	aug-cc-pVDZ	aug-cc-pVTZ	aug-cc-pVQZ	Sadlej_pVTZ
hartree fock	HF	1.3710 31	1.2024 44	1.1861 45	1.1818 45	1.2075 49	1.1791 45	1.6780 44	1.1812 45	1.1772 45	1.3571 46	1.2516 29	1.5103 4	1.2499 58	1.1850 45	1.1757 45	0.8847 6	1.1545 40	1.2110 45	1.2186 10	0.7555 1
hartree fock	ROHF	1.0865 2	1.0842 2	1.0842 2	1.0843 2	1.1728 4	1.0856 2	1.0855 2	1.0849 2	1.0858 2	1.0859 2				1.0924 2	1.0837 2
density functional	LSDA	1.2451 34	1.2297 43	1.2297 43	1.2278 43	1.2221 43	1.2215 43	1.2097 40	1.2169 43	1.2121 43	1.2215 43	0.7640 2			1.2236 43	1.2119 43		1.2186 38	0.7641 2
	SVWN		1.2173 43			1.2091 43		1.2098 43
	BLYP	1.5954 31	1.2312 45	1.2312 45	1.2000 44	1.1949 44	1.2097 45	1.1988 40	1.2012 45	1.1963 45	1.5283 41				1.5509 45	1.1808 40		1.4856 24
	B1B95	1.3756 36	1.3753 45	1.3753 45	1.3726 45	1.3689 45	1.3691 45	1.2432 45	1.3637 45	1.3600 45	1.4461 34				1.3710 45	1.3584 45	0.9508 1	1.4456 33	0.7544 1	0.7504 1
	B3LYP	1.3932 36	1.2255 49	1.2051 45	1.1996 45	1.2198 49	1.1945 45	1.2160 49	1.1904 45	1.1521 28	1.4882 46	1.9072 20	1.4710 4	1.2413 64	1.1992 45	1.1835 45	1.0770 9	1.2010 43	1.0892 25	1.1857 10	0.7689 1
	B3LYPultrafine		1.4551 4			1.2198 49		1.3375 11					1.4709 4						1.4713 4
	B3PW91	1.1046 18	1.2010 45	1.2010 45	1.1955 45	1.1911 45	1.1907 45	1.1910 45	1.1852 45	1.1462 28	1.5081 41				1.1943 45	1.1795 45		1.4395 29
	mPW1PW91	1.1617 23	1.1855 40	1.2023 37	1.3246 40	1.1757 40	1.1752 40	1.1756 40	1.1696 40	1.1788 45	1.5047 41				1.1792 40	1.1641 40		1.4676 24
	M06-2X					1.2123 49
	PBEPBE	1.1167 18	1.2261 41	1.2197 37	1.2237 36	1.2279 45	1.2019 41	1.2368 45	1.1994 41	1.1898 45	1.6152 46	1.9131 20	1.4570 4		1.2052 41	1.3828 41	0.9536 1	1.1453 18	1.1222 21	0.7621 1	0.7764 1
	PBEPBEultrafine		1.4424 4			1.2466 40		1.5587 1					1.4594 4						1.4594 4
	HSEh1PBE					1.2180 47
Moller Plesset perturbation	MP2FC	1.1265 22	1.2144 44	1.1884 40	1.1869 40	1.6378 49	1.1699 40	1.1966 44	1.1734 40	1.1793 45	1.6812 40	0.7366 1	1.4614 4	1.2365 64	1.1927 45	1.5576 40	0.8429 5	1.1668 40	1.0509 9	0.8026 5	0.7660 1
	MP2FU	1.1667 20	1.1882 40	1.2319 35	1.2303 35	1.1746 40	1.1688 40	1.1697 40	1.2080 37	1.1420 28	1.1365 21				1.2132 37	1.1995 35	0.8428 5	1.0761 6	0.7512 1	0.7471 1
	MP3					1.1923 44
	MP4		1.0984 18		1.3908 5	1.0874 15			0.8853 5	0.9549 5						0.9026 7
	B2PLYP					1.2053 43		1.1966 46
Configuration interaction	CID		1.2487 30	1.2453 26	1.2412 26	1.1829 35			1.1546 20	1.2788 5						0.7421 3
Configuration interaction	CISD		1.2039 33	1.2459 26	1.2417 26	1.1716 40			1.2333 26	1.2791 5						0.7426 3
Quadratic configuration interaction	QCISD	1.1545 11	1.1926 40	1.1799 33	1.1916 32	1.1789 40	1.1585 33	1.1919 36	1.1642 35	1.4359 26	1.0514 10				1.2444 31	0.9310 6			0.7577 1
Quadratic configuration interaction	QCISD(T)					1.0885 15	0.9121 4	0.9121 4	0.9984 6						0.9025 7	0.8610 7		0.9005 3	0.8457 4
Coupled Cluster	CCD	1.1545 11	1.1961 38	1.2217 30	1.2202 30	1.1778 40	1.1574 33	1.1582 33	1.1619 35	1.0784 16	1.0503 10	0.7420 1			1.1758 25	0.8488 4	0.7412 1	0.7610 1	0.7497 2	0.7413 1
	CCSD		0.7498 1			0.9614 10	0.9701 3	0.7385 2	1.0477 5			0.7422 1			0.7609 2	0.7426 2		0.7618 1	0.7430 1
	CCSD(T)		1.3332 5			1.1179 14	0.9720 6	0.9121 4	0.9981 6			0.7422 3			0.9039 4	0.9311 6	0.8997 4	0.8658 4	0.8251 5	0.8438 4
	CCSD(T)=FULL					1.1185 5											0.9770 1			0.7538 1

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	1.1902 45	1.1865 45	1.1899 45	1.1930 46	1.1819 41	1.1847 45
density functional	LSDA	0.7639 1	0.7639 1	0.7640 1	0.7640 1	0.7639 1	0.7639 1
	B1B95	1.2495 44	1.2365 43	1.0741 13	1.0742 13	1.0728 13	1.0728 13
	B3LYP	1.2119 45	1.2066 45	1.2024 45	1.2046 46	1.2137 46	1.2046 45
Moller Plesset perturbation	MP2FC	1.2147 45	1.1997 45	1.2069 45	1.1875 41	1.2054 41	1.1948 40

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.