III.G.1.a.

Comparison of levels of theory for Se-Se

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	PM3	2.1420 3
semi-empirical	PM6	2.2034 4
composite	G2	2.1475 4
composite	CBS-Q	2.1499 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
hartree fock	HF	2.1646 4	2.2766 4	2.1477 4	2.2317 4	2.1475 4	2.1475 4	2.1490 4	2.1583 4	2.1583 4	2.1098 4	2.1366 1	2.1595 4	2.1531 4	2.1478 4	2.1456 4	2.1564 4	2.1508 3	2.1452 4
hartree fock	ROHF	2.1528 1	2.2636 1	2.1375 1	2.2160 1	2.1985 2	2.1370 1	2.1388 1	2.1466 1	2.1466 1	2.0997 1			2.1418 1	2.1360 1		2.1442 1
density functional	LSDA	2.2088 4	2.1966 2	2.1309 2	2.2691 4	2.1804 4	2.1804 4	2.1804 4	2.1883 4	2.1883 4	2.1339 4			2.1910 3	2.1763 4	2.1841 2	2.1874 4	2.1785 3	2.1829 2
	SVWN		2.3049 4			2.1704 1		2.1804 4
	BLYP	2.2445 4	2.3256 3	2.2239 4	2.3321 4	2.2650 3	2.2650 3	2.2352 4	2.2781 3	2.2781 3	2.1845 4			2.2457 4	2.2343 4
	B1B95	2.2013 4	2.2023 4	2.1691 4	2.2631 4	2.1749 3	2.1722 4	2.1724 4	2.1836 4	2.1836 4	2.1295 4			2.1801 4	2.1715 4	2.1732 3	2.1792 4	2.1743 3	2.2170 2
	B3LYP	2.2189 4	2.3276 4	2.1940 4	2.2933 4	2.2017 4	2.2017 4	2.2018 4	2.2118 4	2.2118 4	2.1547 4		2.2122 4	2.2099 4	2.1997 4	2.1975 4	2.2096 4	2.1986 4	2.1967 4
	B3LYPultrafine					2.2054 3
	B3PW91	2.2112 4	2.3147 4	2.1799 4	2.2753 4	2.1838 4	2.1838 4	2.1836 4	2.1935 4	2.1935 4	2.1395 4			2.1915 4	2.1821 4
	mPW1PW91	2.2047 4	2.3072 4	2.1734 4	2.2669 4	2.1762 4	2.1762 4	2.1762 4	2.1860 4	2.1860 4	2.1331 4			2.1836 4	2.1749 4
	M06-2X					2.1668 4
	PBEPBE	2.2286 4	2.3411 4	2.2016 4	2.3053 4	2.2073 4	2.2073 4	2.2068 4	2.2216 3	2.2216 3	2.1601 4			2.2165 4	2.2072 4	2.2154 2	2.2066 2	2.1968 2	2.2139 2
	HSEh1PBE					2.1812 3
Moller Plesset perturbation	MP2FC	2.2678 3	2.4290 4	2.2099 4	2.3872 4	2.2208 4	2.2208 4	2.2213 4	2.2319 4	2.2319 4	2.1562 4		2.2208 4	2.2189 4	2.1727 1	2.1602 1	2.2242 4		2.1579 1
	MP2FU	2.2677 3	2.4297 4	2.2083 4	2.3881 4	2.2138 4	2.2138 4	2.2144 4	2.2258 4	2.2258 4	2.1382 4			2.2169 4	2.1676 1	2.1590 1	2.2121 2
	ROMP2		2.3898 1	2.1940 1	2.3531 1	2.2062 1	2.2062 1	2.2091 1	2.2191 1	2.2191 1	2.1462 1			2.2023 1	2.1823 1		2.2142 1
	MP3					2.2128 3
	MP4		2.3979 4			2.2261 4				2.2389 4	2.1465 1				2.2057 3
	B2PLYP					2.2087 4		2.2094 4
Configuration interaction	CID		2.3599 3	2.1851 3	2.3171 3	2.1890 4			2.2008 3
Configuration interaction	CISD		2.3638 3	2.1867 3	2.3217 3	2.1907 4			2.2031 3
Quadratic configuration interaction	QCISD	2.2197 1	2.3820 4	2.1983 4	2.3396 4	2.2075 4	2.2075 4	2.2142 3	2.2170 4	2.2170 4	2.1487 4			2.2063 4	2.1837 4
Quadratic configuration interaction	QCISD(T)					2.2291 3								2.2293 3	2.2066 3		2.2350 3	2.2010 1
Coupled Cluster	CCD	2.2190 1	2.3748 4	2.1948 4	2.3318 4	2.2037 4	2.2037 4	2.2094 3	2.2119 4	2.2119 4	2.1447 4			2.2018 4	2.1838 3		2.2118 3
	CCSD					2.2064 4
	CCSD(T)					2.2139 2		2.2033 1						2.2211 4	2.1994 4		2.2274 4	2.2004 1
	CCSD(T)=FULL					2.2219 3

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	2.2474 3		2.2474 3		2.2790 4	2.2442 4
hartree fock	ROHF	2.2276 1		2.2276 1		2.2645 1	2.2275 1
density functional	B1B95	2.2812 1
density functional	B3LYP	2.3080 4		2.3080 4		2.3442 4	2.3066 4
Moller Plesset perturbation	MP2FC	2.3948 4		2.3948 4		2.4412 4	2.3872 4
Moller Plesset perturbation	ROMP2	2.3710 1		2.3710 1		2.4009 1	2.3623 1

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.