Entry C4H4_ccpvdz_JW_HEA_v4_casscf_tapered__sha256_5b0a919ded51c8e6 | QEncode

VQE Gap

9.6368e-3 Ha

CASCI ref

-153.673427 Ha

Qubits (tapered)

CCSD(T) corr.

-5.957e-1 Ha

Molecule / Problem

NameC4H4

Basis setcc-pvdz

GeometryC 0.673 0.783 0.0; C -0.673 0.783 0.0; C -0.673 -0.783 0.0; C 0.673 -0.783 0.0; H 1.377 1.602 0.0; H -1.377 1.602 0.0; H -1.377 -1.602 0.0; H 1.377 -1.602 0.0

Charge0

Spin0

Active electrons4

Active orbitals4

Orbital optimizationCASSCF

Encoding / Circuit

Qubit mappingjordan-wigner

Ansatz typehea

Ansatz reps (HEA)2

TaperingZ2 symmetry — 2 symmetries removed

Qubits (original)8

Qubits (tapered)6

Num parameters18

Circuit depth11

2Q gates10

Energy Results

HF energy-153.6528244194 Ha

MP2 energy-154.1870717643 Ha

CCSD energy-154.2235763592 Ha

CCSD(T) energy-154.2485698632 Ha

CASSCF energy-153.6734265502 Ha

CASCI ground state-153.6734265503 Ha

VQE best energy-153.6637897478 Ha

|VQE − CASCI| gap9.636802e-3 Ha

CCSD(T) correlation-5.957454e-1 Ha

Optimizer / Run Config

AlgorithmCOBYLA

Multistart runs8

Max iterations500

Total func evals4,000

Num parameters18

Backenddefault.qubit

Provenance / Reproducibility

Entry IDC4H4_ccpvdz_JW_HEA_v4_casscf_tapered__sha256_5b0a919ded51c8e6

Schema version4.0.0

Created (UTC)2026-07-16T13:09:45.664646+00:00

SHA-256 hash5b0a919ded51c8e632dd665208883c453d3b6cab39e952829750444fe893ecac

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 C4H4 \

--mapping jordan_wigner \

--ansatz-type hea \

--reps 2 \

--orbital-opt casscf \

--multistart 8 \

--max-iter 500 \

--out-dir releases/v4/db

View raw JSON on GitHub