III.G.1.a.

Comparison of levels of theory for H-Si

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	1.4481 16
	PM3	1.4928 44
	PM6	1.4957 51
composite	G2	1.4836 46
	G3	1.4836 46
	G3B3	1.4988 46
	CBS-Q	1.4846 44

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(T+d)Z	cc-pCVDZ	cc-pCVTZ
hartree fock	HF	1.4388 41	1.4963 46	1.4820 46	1.5032 46	1.4822 42	1.4843 46	1.4829 46	1.4829 46	1.4856 44	1.4845 44	1.4767 28	1.4917 51	1.4950 46	1.4870 46	1.4842 43	1.4942 46	1.4861 46	1.4855 39	1.4756 34	1.4939 5	1.4839 5
hartree fock	ROHF	1.4610 10	1.5125 14	1.4937 14	1.5258 10	1.4961 14	1.4966 14	1.4944 14	1.4957 14	1.5016 10	1.4991 10			1.5092 14	1.5001 14	1.4991 10	1.5099 10	1.5008 10	1.4975 10
density functional	LSDA	1.4683 44	1.5220 44	1.5089 44	1.5296 44	1.5107 44	1.5099 44	1.5091 44	1.5080 44	1.5079 44	1.5064 44			1.5204 44	1.5066 44	1.5257 12	1.5170 44	1.5248 14	1.5244 12
	SVWN		1.5134 51			1.4920 46		1.4986 51
	BLYP	1.4775 41	1.5216 46	1.5067 46	1.5288 46	1.5098 46	1.5079 46	1.5070 46	1.5058 46	1.5059 44	1.5046 44			1.5186 46	1.5043 46		1.5060 28
	B1B95	1.4607 44	1.5019 46	1.4949 46	1.5137 46	1.4957 46	1.4957 46	1.4947 46	1.4941 46	1.4948 44	1.4934 44			1.5056 46	1.4935 46	1.5127 12	1.5043 43	1.5094 14	1.5113 12
	B3LYP	1.4640 44	1.5108 46	1.4963 46	1.5176 46	1.4988 46	1.4975 46	1.4965 46	1.4955 46	1.5112 16	1.4950 44	1.4840 28	1.5033 51	1.5080 46	1.4952 46	1.4931 41	1.5048 46	1.4942 46	1.4930 39	1.4824 34	1.5038 5	1.4905 5
	B3LYPultrafine					1.4988 46		1.5018 4
	B3PW91	1.4848 16	1.5126 46	1.4986 46	1.5181 46	1.4997 46	1.4989 46	1.4979 46	1.4983 46	1.5132 16	1.4973 44			1.5091 46	1.4981 46		1.4994 28
	mPW1PW91	1.4757 19	1.5101 46	1.5039 20	1.5156 46	1.4973 46	1.4967 46	1.4956 46	1.4962 46	1.4969 44	1.4952 44			1.5069 46	1.4963 46		1.4975 28
	M06-2X					1.4784 51
	PBEPBE	1.4980 16	1.5249 46	1.5223 18	1.5479 18	1.5122 46	1.5111 46	1.5101 46	1.5103 46	1.5102 44	1.5089 44	1.4981 28		1.5222 45	1.5095 46	1.5290 12	1.5109 4	1.5012 30	1.5274 12	1.5445 1
	PBEPBEultrafine					1.5038 32
	HSEh1PBE					1.4861 51
Moller Plesset perturbation	MP2FC	1.4714 16	1.5092 46	1.4893 46	1.5180 46	1.4929 46	1.4830 46	1.4816 46	1.4895 45	1.4841 44	1.4875 35		1.4922 51	1.4973 46	1.4875 44	1.4985 11	1.4986 45	1.4895 41	1.4899 6	1.4762 34	1.4949 5	1.4832 5
	MP2FU	1.4715 16	1.5093 46	1.4954 20	1.5280 20	1.4926 46	1.4820 46	1.4806 46	1.4889 46	1.4959 16	1.4932 16			1.4967 46	1.4947 18	1.4910 9	1.4995 8	1.4979 10	1.4699 5	1.4715 34	1.4946 5	1.4798 5
	ROMP2	1.4699 12	1.5201 12	1.4986 12	1.5323 12	1.5030 12	1.4930 12	1.4908 12	1.5002 12	1.4944 12	1.4935 12			1.5095 12	1.4987 12	1.4993 10	1.5088 12	1.5024 10	1.4989 10
	MP3					1.4970 46
	MP4		1.5265 30			1.5002 46			1.4911 25	1.5026 14					1.5012 12
	B2PLYP					1.4806 51		1.4726 47
Configuration interaction	CID		1.5304 18	1.5002 20	1.5357 20	1.4966 46			1.4938 45						1.4913 10
Configuration interaction	CISD		1.5286 28	1.5011 20	1.5369 20	1.4971 46			1.5028 20						1.4919 10
Quadratic configuration interaction	QCISD	1.4491 2	1.5203 46	1.5143 30	1.5410 20	1.5011 46	1.4924 30	1.4871 40	1.4978 46	1.4881 42	1.5042 14			1.5022 45	1.5028 26					1.5236 1
Quadratic configuration interaction	QCISD(T)		1.5087 2			1.5041 41	1.4878 12	1.4869 12	1.4929 27					1.5155 24	1.5054 24		1.5232 14	1.5152 12
Coupled Cluster	CCD	1.4489 2	1.5275 30	1.5030 20	1.5394 20	1.5003 46	1.4913 30	1.4914 28	1.4975 45	1.5043 14	1.5026 14			1.5011 45	1.5018 26		1.5247 12	1.4900 7			1.4977 5	1.4872 5
	CCSD		1.5079 2			1.5012 44	1.4868 12	1.4858 12	1.4914 27					1.5016 12	1.4924 12
	CCSD(T)		1.5310 3			1.4992 37	1.4804 26	1.4869 12	1.4928 27	1.5240 1		1.5262 1		1.5130 26	1.4999 32	1.4648 3	1.5185 16	1.5026 12		1.4923 15	1.4996 5	1.4889 5
	CCSD(T)=FULL					1.5203 12								1.5000 5	1.4880 5	1.4538 3					1.4994 5	1.4858 5

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	1.5117 46	1.4975 44	1.5074 46	1.4985 44	1.4834 46	1.4930 46
density functional	B1B95	1.5162 27	1.5037 30	1.5152 2	1.5062 2	1.4924 2	1.4974 2
density functional	B3LYP	1.5247 46	1.5098 44	1.5248 46	1.5118 44	1.4978 46	1.5066 46
Moller Plesset perturbation	MP2FC	1.5278 46	1.5077 44	1.5226 46	1.5070 44	1.4975 46	1.5052 46

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.