An Assessment of Alternative Low Level Calculation Methods for the Initial Selection of Conformers of Diastereomeric Esters

Table 3

The number of conformers found by optimization with LLMs and HF/STO-3G (Steps 1 and 2, Step 4 (the first level), resp., Figure 2) as well as with the RefM2 (entire Step 4, Figure 2) within certain energy ranges.

Energy range from 0.00 to 𝑋  [kcal/mol]	RefM2	HF	UFF	Dreiding	AM1	PM3	PM6	MM3	MM+
COFC energy^a	11	11	35	97	87	94	76	55	37
2,50	46	54	35	111	109	159	28	39	71
2,00	43	42	23	81	78	132	27	29	64
1,50	33	42	10	49	60	89	14	26	51
1,00	11	11	6	17	32	41	10	11	26
0,75	9	4	4	13	18	26	10	4	16

aThe COFC energy values for LLMs are given in Table 2.