Entry BeH2_ccpvdz_JW_UCCSD_v4_tapered__sha256_31f7be8f2f7d9f00 | QEncode

VQE Gap

6.6461e-6 Ha

CASCI ref

-15.768411 Ha

Qubits (tapered)

CCSD(T) corr.

-6.896e-2 Ha

Molecule / Problem

NameBeH2

Basis setcc-pvdz

GeometryH 0.0 0.0 -1.30; Be 0.0 0.0 0.0; H 0.0 0.0 1.30

Charge0

Spin0

Active electrons4

Active orbitals4

Orbital optimizationHF

Encoding / Circuit

Qubit mappingjordan-wigner

Ansatz typeuccsd_tapered

Ansatz reps (HEA)1

TaperingZ2 symmetry — 5 symmetries removed

Qubits (original)8

Qubits (tapered)3

Num parameters8

Circuit depth14

2Q gates8

Note on UCCSD circuit metrics

UCCSD uses exponential Pauli operators (exp(iθH)) that are symbolic before compilation. Circuit depth and 2-qubit gate counts are not reported here — they depend on the target hardware and transpiler.

Energy Results

HF energy-15.7664276149 Ha

MP2 energy-15.8183028207 Ha

CCSD energy-15.8349590260 Ha

CCSD(T) energy-15.8353910120 Ha

CASCI ground state-15.7684109880 Ha

VQE best energy-15.7684043419 Ha

|VQE − CASCI| gap6.646119e-6 Ha

CCSD(T) correlation-6.896340e-2 Ha

Optimizer / Run Config

AlgorithmCOBYLA

Multistart runs1

Max iterations500

Total func evals272

Num parameters8

Backenddefault.qubit

Provenance / Reproducibility

Entry IDBeH2_ccpvdz_JW_UCCSD_v4_tapered__sha256_31f7be8f2f7d9f00

Schema version4.0.0

Created (UTC)2026-07-15T13:20:22.330397+00:00

SHA-256 hash31f7be8f2f7d9f008f5e8fa13d9eb66df388d1ee38cfdf22dd13b4b7acfd78f9

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 BeH2 \

--mapping jordan_wigner \

--ansatz-type uccsd \

--multistart 1 \

--max-iter 500 \

--out-dir releases/v4/db

View raw JSON on GitHub