III.G.1.a.

Comparison of levels of theory for Mg-O

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	2.7023 1
	PM3	1.7374 4
	PM6	1.7128 4
composite	G2	1.7668 4
	G3	1.7667 4
	G3B3	1.8007 4
	CBS-Q	1.7822 3

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-pCVDZ	cc-pCVTZ
hartree fock	HF	1.8033 4	1.8915 4	1.7490 4	1.9931 4	1.7668 4	1.7650 4	1.8308 3	1.7749 4	1.7754 4	1.7533 4	1.7386 2	1.8309 4	1.7730 4	1.7671 3	1.7527 4	1.8600 2	1.7941 4	1.7587 3	1.7426 1	1.7159 1
hartree fock	ROHF		1.7269 1	1.7248 1		1.7515 2	1.7621 1	1.7821 1	1.7655 1
density functional	LSDA	1.7318 4	1.7649 4	1.7578 4	1.8021 4	1.7870 4	1.7861 4	1.7995 4	1.7943 4	1.7953 4	1.7715 4			1.7921 4	1.7783 4	1.7933 2	1.7879 4	1.7984 2	1.7935 2
	SVWN		1.7781 4			1.7870 4		1.7930 4
	BLYP	1.7613 4	1.8050 4	1.7838 4	1.8312 4	1.8196 4	1.8188 4	1.8360 4	1.8296 4	1.8308 4	1.8058 4			1.8458 2	1.8343 2		1.8041 2
	B1B95	1.7429 4	1.7711 4	1.7648 4	1.8127 4	1.7932 4	1.7933 4	1.8066 4	1.8000 4	1.8000 4	1.7807 4			1.7969 4	1.7846 4	1.8027 2	1.7883 2	1.8213 1	1.8036 2	1.7442 1	1.7306 1
	B3LYP	1.7498 4	1.7875 4	1.7679 4	1.8155 4	1.8007 4	1.7994 4	1.8149 4	1.8082 4	1.8344 2	1.7844 4	1.7563 2	1.8224 4	1.8035 4	1.8151 2	1.7877 4	1.8253 2	1.7939 4	1.7847 4	1.7474 1	1.7349 1
	B3LYPultrafine					1.8008 4
	B3PW91	1.7569 2	1.8030 3	1.7689 4	1.8145 4	1.7973 4	1.7961 4	1.8096 4	1.8038 4	1.8306 2	1.7810 3			1.8268 2	1.8097 2		1.7786 2
	mPW1PW91	1.7550 2	1.7839 4	1.8010 2	1.8116 4	1.7940 4	1.7927 4	1.8060 4	1.7998 4	1.8004 4	1.7799 4			1.8239 2	1.8064 2		1.7752 2
	M06-2X					1.7859 4
	PBEPBE	1.7631 2	1.8032 4	1.8188 2	1.8745 2	1.8157 4	1.8150 4	1.8301 4	1.8244 4	1.8259 4	1.8024 4	1.7841 2		1.8210 4	1.8090 4	1.8226 2			1.8238 2
	PBEPBEultrafine					1.7982 2
	HSEh1PBE					1.7955 4
Moller Plesset perturbation	MP2FC	1.7484 2	1.7676 4	1.7727 4	1.8003 4	1.8009 4	1.7990 4	1.8378 4	1.8006 4	1.8030 4	1.7874 4		1.8313 4	1.7979 4	1.7898 3	1.7893 3	1.8410 3	1.8019 4	1.8212 3	1.7346 1	1.7371 1
	MP2FU	1.7508 2	1.7681 4	1.8203 2	1.8510 2	1.7997 4	1.7931 4	1.8352 4	1.7991 4	1.8374 2	1.8070 2			1.8037 3	1.7862 3	1.7817 3	1.7800 2	1.7373 1	1.8421 2	1.7345 1	1.7348 1
	MP3					1.8021 4
	MP4		1.8081 2			1.8058 4			1.7516 2	1.8634 2					1.8011 4
	B2PLYP					1.7944 4		1.8020 4
Configuration interaction	CID		1.8174 2	1.7974 2	1.8365 2	1.7922 4			1.7909 4
Configuration interaction	CISD		1.8258 2	1.8047 2	1.8473 2	1.7973 4	1.7736 1		1.8168 2
Quadratic configuration interaction	QCISD		1.8451 4	1.8483 1	1.9087 1	1.8209 3	1.8523 1	1.8247 3	1.8173 3	1.8330 2	1.8320 1			1.8199 4	1.7994 3
Quadratic configuration interaction	QCISD(T)					1.8151 4			1.7939 2					1.8417 2	1.8205 2		1.8541 1	1.8370 1
Coupled Cluster	CCD		1.8204 2	1.8020 2	1.8401 2	1.8001 4	1.8104 2	1.8911 2	1.7991 4	1.8163 2	1.7933 2			1.7993 4	1.7855 3		1.8818 2	1.8619 2		1.7851 1	1.7643 1
	CCSD					1.8099 4			1.7914 2
	CCSD(T)		1.7751 1			1.7914 2	1.7872 2	1.7909 1	1.7833 2	1.7754 1		1.7603 1		1.8433 2	1.7979 4		1.8520 1	1.8007 2		1.7721 1	1.7526 1
	CCSD(T)=FULL					1.8119 3								1.7747 1	1.7536 1					1.7693 1	1.7430 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	1.8198 3	1.7853 4	1.7850 3	1.7671 4	1.7893 4	1.9716 4
density functional	B1B95	1.8010 2	1.7792 2
density functional	B3LYP	1.8496 4	1.8145 4	1.8274 4	1.8040 4	1.7984 4	1.8231 4
Moller Plesset perturbation	MP2FC	1.8271 4	1.8073 4	1.8014 4	1.7948 4	1.8024 4	1.8088 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.