Table 2. Vibrational Frequencies for gauche-Ethanol^a.

mode	scl-harm (ref (77))b	scl-harm (ref (76))c	MM (11 modes)	MM (15 modes)	AS SCIVR	expt (ref (77))
7(CO–str)	1063	1064	****	1085	1060	1066
8(CH2–rck)	1119	1129	****	1124	1115	1117
9(CH2–twst)	1259	1256	****	1259	1247	1249
10(COH–bnd)	1345	1348	****	1337	1332	1342
11(CH2–wag)	1373	1376	1370	1370	1369	1373
12(CH3–sdef)	1396	1391	1393	1393	1386	1394 (1430)
13(CH3–adef′)	1461	1464	1448	1447	1448	1460
14(CH3–adef″)	1466	1467	1454	1454	1451	1465 (1460)
15(CH2–sdef)	1490	1489	1480	1480	1475	1493 (1460)
16(CH2–sstr)	2886	2874	2867d	2880d	2885	2912
17(CH3–sstr)	2912	2924	2874d	2923d	2909	2936
18(CH2–astr)	2978	2965	2927d	2950d	2957	2972
19(CH3–astr′)	2996	2990	2958d	2979d	2977	2987
20(CH3–astr″)	3015	3010	2976d	2978d	2985	2994
21(OH–str)	3579	3662	3659	3653	3655	3662
MAE	13	8	22	12	10

^aHarmonic, MULTIMODE (4MR), AS SCIVR, and experimental IR gas values. Experimental values in parentheses refer to the Raman experiment. MAE is the mean absolute error with respect to the closest experimental frequency.

^bScaled harmonic at MP2/6-31G(d) level. Scaling factors: 1.0 for heavy atom bend; 0.88 for CH stretches (str) and deformations (def); 0.90 for all other modes.

^cScaled harmonic at DFT/B97-3c level. Scaling factor 0.979.

^dThese states are mixed ones. See text and Table 4 for details. In the fourth column, the values 2950 for mode 18 and 2979 for mode 19 were employed in the MAE calculation.