oxazole+CH3 C4H5NO

B_15f6f91ace · SMILES Cc1cocn1 · InChIKey PUMREIFKTMLCAF-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.

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

27 vibrational modes; imaginary modes negative. Shift = ωB97X − B3LYP.

Band heights are not computed for this molecule yet (no dipole derivatives); positions only, at unit height. High wavenumbers on the left; the table below is the same data.

#	B3LYP (cm⁻¹)	ωB97X (cm⁻¹)	shift
1	132.0	110.8	-21.2
2	269.1	281.7	+12.6
3	334.1	337.5	+3.4
4	631.9	643.6	+11.7
5	662.4	668.8	+6.4
6	674.5	687.9	+13.4
7	747.6	778.3	+30.7
8	830.2	874.4	+44.2
9	933.3	940.4	+7.1
10	977.1	989.6	+12.6
11	1030.1	1033.9	+3.8
12	1083.5	1087.6	+4.1
13	1097.0	1105.1	+8.2
14	1142.3	1167.7	+25.3
15	1255.8	1258.7	+2.8
16	1289.3	1306.3	+17.1
17	1353.0	1375.8	+22.9
18	1447.3	1455.9	+8.7
19	1506.0	1507.1	+1.1
20	1519.5	1528.3	+8.8
21	1570.4	1597.2	+26.7
22	1650.1	1679.9	+29.8
23	3053.8	3087.7	+33.9
24	3110.2	3159.8	+49.6
25	3134.0	3180.0	+46.0
26	3294.7	3333.4	+38.7
27	3313.0	3351.8	+38.8

Structure

2D depiction from the SMILES.

Status ladder

Listed
Cheap level done — 2026-09-28, ubuntu-32gb-hel1-16
Correction predicted — not yet: the learned layer is training
Spectrum predicted — not yet: the learned layer is training
Anchored
Validated

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Second route

Analytic Hessian (pyscf, grid 99/590) against the corpus finite differences: b3lyp max |Δω| 2 cm⁻¹; wb97x max |Δω| 36 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-hel1-16, 2026-09-27 23:56:46 → 2026-09-28 00:01:44, 298 s, peak 1.43 GB, deck 9e27bf8e9348
Imaginary modes: B3LYP 0, ωB97X 0
Source files: corpus factory · manifest