imidazole+CH3 C4H6N2

B_151c8ce719 · SMILES Cc1c[nH]cn1 · InChIKey XLSZMDLNRCVEIJ-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)

30 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	110.9	91.6	-19.2
2	265.2	277.0	+11.8
3	338.5	341.6	+3.1
4	480.2	533.4	+53.2
5	650.9	666.0	+15.1
6	664.5	671.3	+6.8
7	687.7	702.6	+14.9
8	717.9	752.2	+34.3
9	802.7	849.5	+46.8
10	948.0	954.8	+6.8
11	978.2	992.8	+14.6
12	1013.0	1016.2	+3.1
13	1081.5	1084.9	+3.3
14	1099.0	1106.0	+7.0
15	1139.1	1155.3	+16.2
16	1254.3	1261.5	+7.2
17	1299.5	1318.6	+19.1
18	1359.8	1383.9	+24.1
19	1445.1	1452.8	+7.7
20	1471.7	1497.1	+25.4
21	1507.3	1509.3	+2.1
22	1520.7	1529.4	+8.6
23	1541.3	1564.7	+23.4
24	1618.9	1645.9	+27.0
25	3047.3	3081.7	+34.5
26	3101.2	3151.6	+50.4
27	3124.6	3171.1	+46.5
28	3263.7	3304.3	+40.6
29	3286.1	3327.0	+40.9
30	3652.6	3703.2	+50.6

Structure

2D depiction from the SMILES.

Status ladder

Listed
Cheap level done — 2026-09-28, ubuntu-32gb-hel1-18
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| 1 cm⁻¹; wb97x max |Δω| 40 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-hel1-18, 2026-09-28 01:06:14 → 2026-09-28 01:12:13, 359 s, peak 1.52 GB, deck 9e27bf8e9348
Imaginary modes: B3LYP 0, ωB97X 0
Source files: corpus factory · manifest