QEncode Benchmark
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H4

/jordan wigner/adapt
Certified
Beats CCSD(T)
cc-pvdz

H4_ccpvdz_JW_ADAPT_v4_tapered__sha256_39f9134a722ad612

VQE Gap

9.9417e-3 Ha

CASCI ref

-2.186232 Ha

Qubits (tapered)

5

CCSD(T) corr.

-8.731e-2 Ha

Molecule / Problem

NameH4
Basis setcc-pvdz
GeometryH 0.0 0.0 0.0; H 0.0 0.0 1.0; H 0.0 0.0 2.0; H 0.0 0.0 3.0
Charge0
Spin0
Active electrons4
Active orbitals4
Orbital optimizationHF

Encoding / Circuit

Qubit mappingjordan-wigner
Ansatz typeadapt
Ansatz reps (HEA)1
TaperingZ2 symmetry — 3 symmetries removed
Qubits (original)8
Qubits (tapered)5
Num parameters1
Circuit depth20
2Q gates14

Energy Results

HF energy-2.1664914658 Ha
MP2 energy-2.2312373418 Ha
CCSD energy-2.2529496914 Ha
CCSD(T) energy-2.2538030394 Ha
CASCI ground state-2.1862316746 Ha
VQE best energy-2.1762899658 Ha
|VQE − CASCI| gap9.941709e-3 Ha
CCSD(T) correlation-8.731157e-2 Ha

Optimizer / Run Config

AlgorithmADAPT-VQE (COBYLA inner)
Multistart runs1
Max iterations500
Total func evals20
Num parameters1
Backenddefault.qubit

Provenance / Reproducibility

Entry IDH4_ccpvdz_JW_ADAPT_v4_tapered__sha256_39f9134a722ad612
Schema version4.0.0
Created (UTC)2026-07-16T09:36:29.649030+00:00
SHA-256 hash39f9134a722ad612b32989df04e5a63d47ab23a93e38f5a431b5ce7fe6518070
Python3.11.15
PySCF2.6.2
PennyLane0.45.0
OpenFermion1.6.1
NumPy2.2.6
SciPy1.13.1

Reproduce this result

# Clone repo and install pinned environment

git clone https://github.com/qencode-benchmark/qencode-benchmark

cd qencode-benchmark

pip install -r requirements-v4.txt

# Run this entry

python scripts/generate_entry_v4.py \

--molecule H4 \

--mapping jordan_wigner \

--ansatz-type adapt \

--reps 1 \

--multistart 1 \

--max-iter 500 \

--out-dir releases/v4/db