III.G.1.a.

Comparison of levels of theory for Al-Al

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	2.4592 3
	PM3	2.4829 4
	PM6	2.5251 5
composite	G2	2.8306 4
	G3	2.8306 4
	G3B3	2.8602 4
	CBS-Q	2.8306 4

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	2.4416 3	2.9800 4	2.8153 4	2.9545 4	2.8306 4	2.8306 4	2.8374 4	2.8561 4	2.9138 4	2.7787 4	2.2557 1	2.7496 5	2.8697 4	2.8594 4	2.7711 2	2.8002 4	2.8630 4	2.7691 2
hartree fock	ROHF					2.7769 3
density functional	LSDA	2.4623 4	2.7982 4	2.7853 4	2.8731 4	2.8099 4	2.8099 4	2.8115 4	2.8213 4	2.8213 4	2.7411 2			2.8287 4	2.8125 4		2.8250 4	2.9289 3
	SVWN		2.7986 3			2.8647 2		2.7905 3
	BLYP	2.5283 3	2.9882 4	2.8833 4	2.9852 4	2.9100 4	2.9100 4	2.9104 4	2.9265 4	2.9955 4	2.9017 4			2.9237 4	2.9103 4		2.8060 1
	B1B95	2.4582 4	2.8180 4	2.8033 4	2.8998 4	2.8216 4	2.8220 4	2.8241 4	2.8433 4	2.8433 4	2.8268 4			2.8456 4	2.8366 4	3.0213 1	2.6992 3	2.9542 3	3.0169 1
	B3LYP	2.4738 4	2.9517 4	2.8339 4	2.9416 4	2.8602 4	2.8602 4	2.8620 4	2.8773 4	3.0005 3	2.8583 4	2.5025 1	2.7497 5	2.8794 4	2.8668 4	2.7769 2	2.8768 4	2.8669 4	2.7744 2
	B3LYPultrafine					2.8600 4
	B3PW91	2.4887 3	2.9210 4	2.8036 4	2.9024 4	2.8246 4	2.8246 4	2.8289 4	2.8461 4	2.9668 3	2.8292 4			2.8485 4	2.8377 4		2.7500 1
	mPW1PW91	2.4446 4	2.9120 4	2.9046 3	2.9532 4	2.8140 4	2.8140 4	2.8178 4	2.8361 4	2.9008 4	2.8201 4			2.8384 4	2.8286 4		2.7440 1
	M06-2X					2.7181 4
	PBEPBE	2.5078 3	2.9351 4	2.9496 3	3.0469 3	2.8529 4	2.8529 4	2.8547 4	2.8731 4	2.9422 4	2.8525 4	2.4892 1		2.8711 4	2.8610 4	3.0755 1	3.0859 1	2.7816 2	3.0705 1
	PBEPBEultrafine					2.4966 1
	HSEh1PBE					2.7959 3
Moller Plesset perturbation	MP2FC	2.4653 3	2.9205 4	2.7634 4	2.9552 4	2.7833 4	2.7833 4	2.7877 4	2.8047 4	2.8636 4	2.7548 4		2.7333 5	2.8407 4	2.8110 4	2.4631 1	2.9032 4	2.7633 4	2.4634 1		2.7441 1	2.7179 1
	MP2FU	2.4629 3	2.9775 4	2.7570 4	2.9555 4	2.7753 4	2.7753 4	2.7819 4	2.8025 4	2.9150 3	2.8819 3			2.8335 4	2.7876 4	2.3957 1	2.7547 2	2.9579 1			2.7379 1	2.7080 1
	MP3					2.8355 4
	MP4		3.1590 3			2.7825 4			2.4750 1	2.9124 3					2.8838 2
	B2PLYP					2.7946 3		2.7935 3
Configuration interaction	CID		3.1454 3	2.8586 3	3.1140 3	2.7284 4			2.7506 4
Configuration interaction	CISD		3.1449 3	2.8606 3	3.1128 3	2.7317 4			2.9150 3
Quadratic configuration interaction	QCISD		3.0149 4	2.8573 3	3.1339 3	2.7846 4	2.7846 4	2.7407 4	2.8063 4	2.9133 3	2.9121 3			2.8011 4	2.8133 4
Quadratic configuration interaction	QCISD(T)					2.7824 4			2.3073 1					2.9607 3	2.9172 3		2.9628 3	2.9202 3
Coupled Cluster	CCD		3.0142 4	2.8538 3	3.1320 3	2.7815 4	2.8775 3	2.8849 3	2.8027 4	2.9092 3	2.9108 3			2.8495 4	2.9162 3		2.9594 3	2.9206 3
	CCSD					2.7842 4			2.2851 1
	CCSD(T)					2.7817 4	2.4914 1		2.3021 1			2.7174 1		2.9104 4	2.8691 4	2.9690 1	2.9135 4	2.8721 4		2.8853 3	2.7589 1	2.7234 1
	CCSD(T)=FULL					2.8278 4								2.7519 1	2.7056 1	2.9530 1	2.7571 1	2.6935 1			2.7527 1	2.7160 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	2.9780 4	2.8971 4	2.9894 4	2.8973 4	3.0086 4	3.0947 4
density functional	B1B95	2.8350 1	2.5317 1
density functional	B3LYP	3.0100 4	2.9388 4	3.0158 4	2.9392 4	3.0287 4	3.0936 4
Moller Plesset perturbation	MP2FC	2.9946 4	2.8656 4	3.0038 4	2.8651 4	3.0192 4	3.0984 4

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.