naphthalene+CH3+NO2 C11H9NO2

B_2a99953b49 · SMILES Cc1ccc([N+](=O)[O-])c2ccccc12 · InChIKey FRLVKAJKOYFHKQ-UHFFFAOYSA-N

Cheap level done

finite-difference Hessian noisy

finite-difference Hessian noisy (analytic check differs > 15 cm⁻¹). The finite-difference Hessian and the analytic Hessian of the same geometry differ by more than 15 cm⁻¹ on at least one frequency; the numerical route is the noisy one.

Infrared spectrum at the cheap level (B3LYP/6-31G*, the pipeline's input)

cheap input (B3LYP) bands

How to read this

39 infrared-active bands (500–3500 cm⁻¹); the strongest at 1381 cm⁻¹ (7.2 µm), 357 km/mol.

cheap input (B3LYP): blue curve, sticks orange at the curve's peak scale. Lorentzian, FWHM 10 cm⁻¹; axis in km mol⁻¹ per cm⁻¹.

Band heights from the molecule's dipole derivatives and the same B3LYP Hessian as the listed positions (double harmonic).

Predicted spectrum (rung 3, the learned correction): computed by the pipeline, not drawn on this page; licensed for ring-ip, CH-stretch, CH-oop (decision 65).

How well is this shape known?

measured on (ΔH network v1.3)	spectrum overlap cheap → corrected	height error cheap → corrected
8 unseen simple aromatics (layer A), DFT stand-in for the higher level	0.28 → 0.98	0.23 → 0.10
31 molecules of unseen scaffolds, DFT stand-in for the higher level	0.37 → 0.97	0.51 → 0.24
against coupled cluster	not measured for this version

Overlap: similarity of the two broadened spectra (1 = the same shape). Height error: relative error per band, weighted by height (0 = the same heights). "Corrected" is the learned correction on molecules it never saw; the pipeline serves it for the licensed families. Open: the dipole derivatives themselves are computed at the cheap level (on benzene they differ from coupled cluster by about 20 %).

Structure

2D depiction from the SMILES.

Status ladder

Listed
Cheap level done — 2026-09-29, ubuntu-32gb-hel1-21
Correction predicted — not yet: the learned layer is training
Spectrum predicted — not yet: the learned layer is training
Anchored
Validated

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Harmonic frequencies at the cheap level (deck v1: B3LYP and ωB97X, 6-31G*, at the B3LYP geometry)

63 vibrational modes; imaginary modes negative. Shift = ωB97X − B3LYP; height = B3LYP band height (km/mol).

The B3LYP bands are drawn in the spectrum above; the table adds their heights, the ωB97X positions and the shift.

#	B3LYP (cm⁻¹)	height (km/mol)	ωB97X (cm⁻¹)	shift
1	57.8	0.43	105.7	+48.0
2	88.4	1.07	123.7	+35.3
3	129.6	0.16	136.7	+7.1
4	185.3	0.62	202.3	+16.9
5	196.5	1.66	231.0	+34.5
6	231.1	2.44	245.8	+14.7
7	288.5	0.91	296.7	+8.2
8	303.2	2.27	315.6	+12.5
9	350.0	0.44	354.9	+5.0
10	403.7	1.82	415.1	+11.5
11	427.4	1.35	434.8	+7.4
12	479.4	0.16	487.1	+7.7
13	482.7	1.21	492.8	+10.2
14	531.1	0.30	535.2	+4.1
15	549.5	3.71	557.0	+7.5
16	612.1	3.63	620.2	+8.1
17	637.6	0.83	651.5	+13.8
18	646.9	3.20	655.4	+8.6
19	718.3	0.78	725.9	+7.6
20	748.4	0.45	768.1	+19.8
21	785.6	38.97	796.4	+10.8
22	789.7	22.09	804.1	+14.4
23	801.8	0.51	807.2	+5.4
24	833.7	37.89	849.1	+15.4
25	858.7	16.30	874.0	+15.3
26	888.5	0.37	898.9	+10.3
27	967.4	4.90	992.2	+24.9
28	969.0	2.83	994.3	+25.3
29	982.4	13.85	1001.5	+19.1
30	1003.1	0.09	1029.6	+26.5
31	1025.2	2.81	1036.1	+10.9
32	1066.3	6.73	1072.2	+6.0
33	1075.4	2.69	1084.8	+9.5
34	1092.0	1.00	1100.1	+8.1
35	1172.2	1.26	1171.4	-0.8
36	1191.9	8.14	1198.5	+6.7
37	1199.7	7.54	1201.0	+1.4
38	1225.1	15.16	1236.2	+11.1
39	1270.7	2.44	1271.2	+0.4
40	1301.7	15.29	1308.4	+6.7
41	1370.4	1.09	1361.7	-8.6
42	1380.5	357.28	1401.0	+20.4
43	1410.0	25.50	1431.8	+21.8
44	1422.7	18.76	1439.0	+16.3
45	1443.8	3.11	1457.9	+14.0
46	1473.3	15.85	1479.7	+6.3
47	1500.8	2.27	1521.1	+20.3
48	1514.5	7.78	1521.6	+7.1
49	1528.5	2.23	1538.5	+10.1
50	1567.8	29.69	1596.9	+29.1
51	1612.5	135.57	1636.6	+24.2
52	1632.8	38.19	1666.6	+33.8
53	1661.1	37.26	1687.1	+26.0
54	1677.6	14.32	1720.6	+43.0
55	3046.7	18.94	3082.8	+36.2
56	3099.4	13.51	3150.3	+50.9
57	3136.0	15.69	3183.1	+47.1
58	3191.5	5.48	3234.1	+42.5
59	3198.9	14.06	3241.8	+42.9
60	3206.4	19.44	3248.8	+42.4
61	3223.8	15.37	3267.7	+43.8
62	3249.9	0.55	3293.0	+43.1
63	3277.4	2.97	3321.2	+43.8

Second route

Analytic Hessian (pyscf, grid 99/590) against the corpus finite differences: b3lyp max |Δω| 4 cm⁻¹; wb97x max |Δω| 21 cm⁻¹.

Provenance

Releases: none yet
Entered the corpus as: cores with one or two substituents, enumerated from the parents (layer B)
Run: ubuntu-32gb-hel1-21, 2026-09-28 22:58:14 → 2026-09-29 00:03:15, 3900 s, peak 4.81 GB, deck 9e27bf8e9348
Imaginary modes: B3LYP 0, ωB97X 0
Cheap-level band heights: dipole derivatives dipole_b3lyp_cphf.npz, Hessian hessian_b3lyp.npz
Source files: corpus factory · manifest