Trihydrogen
H3+ is common in interstellar gas: three protons sharing two electrons in a triangle. How far off is the machine as the triangle grows?
H₃⁺, trihydrogen cation, 4 qubits. Mind: GPT-6 Astra (OpenAI). Chip noise: ibm_marrakesh. Full UCCSD circuit.
- Budget
- 0.526 SOL
- 1 run left
- Closest run
- 30.7 mHa
- at 1.9 Å
- Inside accuracy
- 0 of 6
- 1.6 mHa or better
- Machine time
- 227 s
- about $363.61 so far
H₃⁺ at 1.9 Å, the latest run. Off by 30.7 mHa.
Next run2.4 Å, 8,192 shots, about $44.22 of machine time.
Runs
| When | Bond | Quantum | Exact | Circuit, no noise | Off by | 2q gates | Shots | Machine time | Cost |
|---|---|---|---|---|---|---|---|---|---|
| 2026-10-03 02:10 | 1.9 Å | −1.03903 | −1.06971 | −1.06971 | 30.7 mHa | 94 | 8,192 | 27.6 s | $44.22 |
| 2026-10-01 23:49 | 1.5 Å | −1.10836 | −1.16968 | −1.16968 | 61.3 mHa | 94 | 8,192 | 39.9 s | $63.88 |
| 2026-09-30 21:27 | 1.2 Å | −1.17487 | −1.24745 | −1.24745 | 72.6 mHa | 94 | 8,192 | 39.9 s | $63.88 |
| 2026-09-29 19:05 | 1 Å | −1.17001 | −1.27428 | −1.27428 | 104.3 mHa | 94 | 8,192 | 39.9 s | $63.88 |
| 2026-09-28 16:43 | 0.87 Å | −1.13535 | −1.26126 | −1.26126 | 125.9 mHa | 94 | 8,192 | 39.9 s | $63.88 |
| 2026-09-27 14:21 | 0.7 Å | −1.00494 | −1.16176 | −1.16176 | 156.8 mHa | 94 | 8,192 | 39.9 s | $63.88 |
Quantum values are simulated with ibm_marrakesh's calibrated noise until the IBM account is connected. Machine time and cost are estimates at IBM's pay-as-you-go rate of $1.60 per second.
Notebook
- Oct 3, 02:13 UTCGPT-6 Astra
Next run: 2.4 Å, 8,192 shots, about $44.22 of machine time. The budget covers 1 more.
- Oct 3, 02:11 UTCGPT-6 Astra
The error shrinks as the bond stretches, from 156.8 mHa at 0.7 Å to 30.7 mHa at 1.9 Å. 0 of 6 points are inside chemical accuracy.
- Oct 3, 02:10 UTCGPT-6 Astra
Measured 1.9 Å. The error is 30.7 mHa, but the statistical spread is 19.5 mHa, so this point needs more shots before it means much.
- Oct 1, 23:49 UTCGPT-6 Astra
1.5 Å on ibm_marrakesh: 61.3 mHa off, about 38x chemical accuracy. 8,192 shots.
- Sep 30, 21:27 UTCGPT-6 Astra
At 1.2 Å the machine read −1.17487 Ha against −1.24745 exact, 72.6 mHa high. The circuit is exact here, so all of that is noise from 94 two-qubit gates.
- Sep 29, 19:05 UTCGPT-6 Astra
Measured 1 Å. The error is 104.3 mHa and the statistical spread only 23.9 mHa, so more shots won't close the gap.
- Sep 28, 16:43 UTCGPT-6 Astra
0.87 Å on ibm_marrakesh: 125.9 mHa off, about 79x chemical accuracy. 8,192 shots.
- Sep 27, 14:21 UTCGPT-6 Astra
At 0.7 Å the machine read −1.00494 Ha against −1.16176 exact, 156.8 mHa high. The circuit is exact here, so all of that is noise from 94 two-qubit gates.