Table 2.

Deviations of formaldehyde harmonic (Δ_harm), anharmonic (Δ_anh) and scaled harmonic (Δ_scal) frequencies (cm⁻¹) calculated with selected Pople and Jensen’s basis sets from the experimental values

		3-21G			6-31G			6-31G*			6-31+G**			6-311++G**			6-311++G(3df,2pd)
Mode	exp.a	Δharm	Δanh	Δscal	Δharm	Δanh	Δscal	Δharm	Δanh	Δscal	Δharm	Δanh	Δscal	Δharm	Δanh	Δscal	Δharm	Δanh	Δscal
Computation criteria: opt freq=anharm
νas(CH2)	2843	114	−139	0	192	−23	75	125	−129	11	137	−12	32	99	−167	7	99	−165	6
νs(CH2)	2782	129	−60	16	182	9	67	135	−31	22	133	−31	30	102	−60	12	102	−58	11
ν(CO)	1745	15	−18	−53	3	−27	−65	105	78	33	74	48	10	70	44	13	77	50	19
σ(CH2)	1500	76	42	15	60	29	0	63	29	2	37	3	−17	31	−1	−17	32	−1	−16
ρ(CH2)	1250	31	4	−19	24	2	−25	30	9	−20	13	−8	−32	10	−10	−30	16	−5	−23
τ(CH2)	1167	53	26	6	36	16	−11	31	12	−15	26	8	−16	35	14	−3	34	16	−4
RMS		81	65	25	112	20	50	92	64	20	86	24	24	68	75	16	69	74	15
Computation criteria: opt=tight scf=tight INT(Grid = 150590) freq=anharm
νas(CH2)	2843	113	−132	−2	190	5	72	125	−124	10	134	−9	29	98	−29	6	95	−29	3
νs(CH2)	2782	128	−52	15	179	16	64	134	−23	22	130	−25	27	101	−50	11	99	−51	8
ν(CO)	1745	15	−17	−53	2	−28	−65	105	78	33	74	47	10	69	44	12	76	49	18
σ(CH2)	1500	76	43	15	60	28	−1	63	29	2	37	3	−17	31	−1	−17	33	−1	−16
ρ(CH2)	1250	31	6	−19	25	2	−24	30	9	−20	13	−8	−32	10	−9	−30	17	−5	−23
τ(CH2)	1167	52	29	5	36	16	−11	31	12	−15	27	8	−15	35	14	−3	35	17	−3
RMS		80	62	25	111	19	49	92	62	20	84	23	23	67	30	16	67	32	14
		pc-0			pc-1			pc-2			pc-3			pc-4			CBSb
Mode	exp.	Δharm	Δanh	Δscal	Δharm	Δanh	Δscal	Δharm	Δanh	Δscal	Δharm	Δanh	Δscal	Δharm	Δanh	Δscal	Δharm	Δanh	Δscal
Computation criteria: opt freq=anharm
νas(CH2)	2843	176	−69	88	108	−162	17	102	−163	11	96	−165	23	96	−166	23	87	−170	14
νs(CH2)	2782	198	6	111	110	−58	21	105	−58	16	101	−59	29	101	−60	29	94	−63	23
ν(CO)	1745	−28	−60	−78	87	60	30	72	45	16	72	45	26	72	45	26	71	44	26
σ(CH2)	1500	30	−4	−15	32	−1	−15	34	1	−13	33	0	−5	33	−1	−6	30	−3	−8
ρ(CH2)	1250	−21	−39	−56	15	−5	−24	18	−4	−21	18	−4	−14	18	−4	−14	18	−4	−14
τ(CH2)	1167	13	−5	−21	22	5	−15	37	17	0	34	16	4	33	15	3	27	11	−2
RMS		110	41	71	74	74	21	70	73	14	67	74	20	67	74	19	63	76	17
Computation criteria: opt=tight scf=tight INT(Grid = 150590) freq=anharm
νas(CH2)	2843	173	−59	85	107	−25	16	101	−26	10	95	−29	22	95	−29	22	87	−33	14
νs(CH2)	2782	196	18	109	109	−48	20	103	−49	14	99	−51	28	99	−51	27	93	−54	22
ν(CO)	1745	−28	−60	−78	87	61	30	71	45	15	71	45	26	71	44	26	70	44	25
σ(CH2)	1500	30	−3	−15	32	−1	−15	34	1	−13	33	−1	−5	32	−1	−6	30	−4	−8
ρ(CH2)	1250	−21	−38	−57	15	−5	−24	18	−4	−21	18	−4	−13	18	−4	−14	18	−4	−14
τ(CH2)	1167	14	−3	−21	22	4	−14	37	18	0	33	15	4	33	15	3	27	11	−3
RMS		108	38	70	74	33	21	69	30	14	66	31	19	66	31	19	62	32	16

^aFrom [41]

^bEstimated for pc-n where n = 2,3,4 using Eq. 1