Table 1. Calculated relative energies (DE, kcal/mol) and ester torsion j (degrees, torsional angle C6-C5-C9-O10)
 

basis	method	DE	j(4a)	j(4b)
3-21G(*)	HF	-2.55	0.0	179.9
	B3LYP	-2.69	0.0	180.0
6-31G	HF	-1.59	0.0	-179.9
	B3LYP	-1.66	0.0	180.0
6-31G*	HF	-1.32	-8.0	170.3
	B3LYP	-1.31	-4.8	172.6
	MP2	-0.97	-10.6	169.2
6-311G	HF	-1.47	-1.4	179.0
	B3LYP	-1.34	-2.5	177.5
	MP2	-0.75	-8.6	173.6
6-31+G*	HF	-1.07	-10.0	170.2
	B3LYP	-1.04	-4.4	174.4
	MP2	-0.75	-12.2	167.9
6-311G*	HF	-1.17	-7.9	171.6
	B3LYP	-1.19	-4.3	173.7
	MP2	-0.81	-9.0	171.6
6-31G**	HF	-1.37	-7.3	170.6
	B3LYP	-1.34	-4.6	175.0
	MP2	-0.97	-10.2	169.5
6-31+G**	HF	-1.12	-9.3	170.5
	B3LYP	-1.04	-5.0	174.8
	MP2	-0.75	-12.2	168.5