acenaphthene C12H10

A_8d1f3c46b0 · SMILES c1cc2c3c(cccc3c1)CC2 · InChIKey CWRYPZZKDGJXCA-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

36 infrared-active bands (500–3500 cm⁻¹); the strongest at 3199 cm⁻¹ (3.1 µm), 60 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 — 2026-09-18, ubuntu-32gb-hel1-2
Correction predicted — not yet: the learned layer is training
Spectrum predicted — not yet: the learned layer is training
Anchored
Validated

Through the pipeline

This molecule has a recorded run: see it go through the pipeline, station by station, with its spectrum and certificate.

Request a run

Not available on this site yet: the pipeline (a molecule in, its spectrum and certificate out) runs on the project's own computer, with three of the four mode families licensed at the DFT stand-in level. Sign-in will be needed only to request runs; reading stays open.

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

60 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	88.2	0.00	97.1	+8.9
2	168.0	0.72	181.0	+13.0
3	222.9	5.92	227.4	+4.5
4	239.3	0.00	245.3	+5.9
5	423.4	1.20	427.7	+4.3
6	451.5	0.00	458.0	+6.5
7	455.0	0.44	461.3	+6.2
8	478.5	0.17	487.5	+9.0
9	509.5	0.05	514.6	+5.1
10	551.5	0.99	555.2	+3.7
11	569.4	0.18	576.3	+6.9
12	631.7	0.00	645.9	+14.2
13	647.8	0.00	655.0	+7.2
14	665.7	3.12	669.5	+3.7
15	768.4	0.00	773.6	+5.2
16	772.3	6.10	777.3	+5.0
17	806.6	55.58	815.8	+9.2
18	815.3	0.56	819.8	+4.5
19	839.0	0.88	846.5	+7.5
20	863.5	14.88	873.4	+9.9
21	887.8	0.00	912.2	+24.5
22	910.9	0.03	936.8	+26.0
23	953.9	0.34	970.0	+16.0
24	965.9	0.00	993.9	+28.0
25	975.8	1.34	1004.4	+28.6
26	1017.4	0.17	1033.5	+16.0
27	1037.1	0.00	1045.9	+8.8
28	1046.4	2.29	1047.9	+1.5
29	1074.1	0.18	1083.6	+9.4
30	1110.4	1.41	1121.3	+10.8
31	1179.1	0.25	1175.1	-3.9
32	1189.6	0.39	1187.2	-2.5
33	1206.5	1.82	1208.3	+1.9
34	1243.8	0.74	1249.0	+5.2
35	1250.8	0.01	1251.0	+0.2
36	1260.1	1.87	1256.9	-3.2
37	1261.2	0.53	1264.5	+3.4
38	1289.0	0.56	1310.0	+21.0
39	1321.8	0.78	1322.8	+1.0
40	1403.6	2.08	1399.5	-4.0
41	1408.6	14.03	1418.7	+10.1
42	1465.3	1.46	1472.6	+7.3
43	1481.5	0.86	1491.8	+10.3
44	1497.5	0.78	1504.8	+7.4
45	1518.8	0.89	1531.9	+13.1
46	1524.5	0.70	1536.7	+12.2
47	1551.0	3.34	1582.1	+31.1
48	1651.0	7.99	1680.9	+29.9
49	1654.7	13.72	1690.3	+35.6
50	1675.8	8.64	1721.9	+46.1
51	3048.8	19.39	3091.5	+42.6
52	3058.8	49.29	3101.6	+42.8
53	3073.8	0.00	3128.2	+54.3
54	3093.1	36.51	3145.3	+52.2
55	3174.7	0.43	3218.3	+43.6
56	3175.4	1.43	3218.7	+43.2
57	3185.5	5.89	3229.2	+43.7
58	3186.3	38.65	3229.4	+43.1
59	3198.5	60.08	3241.9	+43.4
60	3200.3	16.69	3243.7	+43.3

Second route

Analytic Hessian (pyscf, grid 99/590) against the corpus finite differences: b3lyp max |Δω| 1 cm⁻¹; wb97x max |Δω| 18 cm⁻¹.

Provenance

Releases: layerA2_2026-09-23, layerA2_2026-09-23b, layerA2_2026-09-24, layerA_2026-09-22
Entered the corpus as: parent molecules chosen by hand (benzene, naphthalene, the PAH cores and their relatives) (layer A)
Run: ubuntu-32gb-hel1-2, 2026-09-18 21:20:02 → 2026-09-18 22:03:22, 2599 s, peak 4.23 GB, deck 97ed2d67c66b
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