BECOME › Catalog › Ethanol › PM6 geometry, 6-31G*, CAS(8e,8o)

Ethanol FCIDUMP: PM6 geometry, 6-31G*, CAS(8e,8o)

Download this ethanol FCIDUMP file and certify its ground-state energy. Built from the PM6 (PubChemQC) geometry with the 6-31G* (spherical d) basis, canonical RHF orbitals and a CAS(8e,8o) active space.

↓ Download FCIDUMP · 29.6 kB Certify the ground-state energy

PubChem CID702

Basis6-31G* (spherical d, 54 functions)

Active space8 electrons in 8 orbitals

RHF orbital gap0.6597 Ha (17.95 eV)

The file holds the one- and two-electron integrals of the ethanol active-space (CASCI) Hamiltonian: 8 electrons in 8 orbitals, plus the core energy. Ethanol is one of 2 catalog molecules with formula C₂H₆O, and it has the lowest RHF energy among them. Its RHF HOMO–LUMO gap is 0.6597 Ha (17.95 eV).

All builds of Ethanol are on the Ethanol page.

File facts

Molecule: Ethanol, C₂H₆O, PubChem CID 702
File: pcq702_6-31g_cas8e8o.fcidump
Size: 29,616 bytes, plain text
SHA-256: 14199aece64925c7b73f7e65e42448d7a288ef6f837939a0ed4d159b58000cfe
Orbitals, electrons: NORB = 8, NELEC = 8
RHF energy of this file: −154.0706984695 Ha (reference value)
Core energy (FCIDUMP): −140.7861483284 Ha
Catalog entry: 17291

Active space

Ethanol has 26 electrons in 54 orbitals. Its 9 inactive (doubly occupied) orbitals, 3 core (1s) and 6 valence, hold 18 electrons and are folded into the core energy; 8 orbitals with 8 electrons are active, and the remaining 37 are virtual orbitals outside the active space. Symmetry: C1 (no point-group symmetry used).

Active #	Orbital	Energy (Ha)	Occupation
1	HOMO−3	−0.53672	2
2	HOMO−2	−0.52138	2
3	HOMO−1	−0.47722	2
4	HOMO	−0.43676	2
5	LUMO	0.22293	0
6	LUMO+1	0.26951	0
7	LUMO+2	0.28941	0
8	LUMO+3	0.29863	0

Core energy (FCIDUMP): −140.7861483284 Ha
Nuclear repulsion: 81.2690248530 Ha (from the geometry below)
Geometry: PM6-optimized, PubChemQC

Check it yourself: the RHF energy above is rebuilt from this file alone as

E_RHF = E_core + ∑_i 2h_ii + ∑_i,j (2J_ij − K_ij)

with i, j running over the 4 occupied active orbitals, h the one-electron integrals, J_ij = (ii|jj) and K_ij = (ij|ji).

Build method

Geometry: PM6-optimized, PubChemQC (Nakata et al., B3LYP/6-31G*//PM6 dataset)
Basis: 6-31G* (spherical d), 54 functions
Orbitals: Canonical RHF
Active space: CAS(8e,8o): 4 highest occupied + 4 lowest virtual. The 9 inactive (doubly occupied) orbitals, 3 core (1s) and 6 valence, are kept doubly occupied and folded into the core energy; the other 37 virtual orbitals are dropped.
Build id: pm6.631gs5d.rhfcan.cas8e8o

Download

↓ Download FCIDUMP · 29.6 kB29,616 bytes, plain text

sha256 14199aece64925c7b73f7e65e42448d7a288ef6f837939a0ed4d159b58000cfe

This file is part of the BECOME Quantum Hamiltonian Catalog, released under CC BY 4.0. Full catalog on Zenodo: doi:10.5281/zenodo.23270267.

Load it

The file is plain-text FCIDUMP. In PySCF:

from pyscf.tools import fcidump
h = fcidump.read("pcq702_6-31g_cas8e8o.fcidump")

h holds the one- and two-electron integrals, the core energy (which already includes the 9 inactive orbitals), NORB = 8 and NELEC = 8. Block2 reads the same format.

Geometry

PM6-optimized geometry from PubChemQC (Nakata et al., B3LYP/6-31G*//PM6 dataset), CC BY 4.0. Coordinates in Å. Download XYZ

9
PubChem CID 702 C2H6O | PubChemQC PM6-optimized geometry (CC-BY-4.0) | Angstrom
C      0.9663399300    -0.0341099975     0.0877999936
C      2.4869198198    -0.0116999992     0.0985299929
O      3.0226197810    -1.0924799209     0.8781599364
H      0.5594099595     0.6777099509    -0.6396099537
H      0.5413099608     0.2168899843     1.0655899228
H      0.5915899572    -1.0306599253    -0.1836299867
H      2.8867697909     0.9386499320     0.4960299641
H      2.9179897886    -0.2069799850    -0.9025599346
H      2.6446098084    -1.0901899210     1.7771398712

Neighbors

The catalog has one other C₂H₆O, dimethyl ether. Related molecules, with the RHF energy of each file:

Dimethyl ether (C₂H₆O) −154.0586021697 Ha
Acetaldehyde (C₂H₄O) −152.9116080926 Ha
Ethane (C₂H₆) −79.2277801309 Ha
Methanol (CH₄O) −115.0315911928 Ha

Browse the catalog

Why certify it?

A certificate gives a proven lower bound and a proven upper bound on the exact ground-state energy of this Hamiltonian. Anyone can check it against the file's SHA-256, without our data and without taking our word for it. You choose how far apart the two bounds may be.

Benchmarks: test a method against bounds that are proved, not estimated.
Quantum-hardware validation: check an energy measured on a quantum computer for this exact file against proved bounds.
Reproducibility: the proof is tied to the file's SHA-256, so a reader can confirm exactly which Hamiltonian it covers.

Accuracy

You pick how far apart the lower and upper bounds may be. The request page offers three levels:

Level	Bound width	In hartree
Standard	1 kcal/mol	1.593601437641 × 10⁻³ Ha
Precise	0.001 kcal/mol	1.593601437641 × 10⁻⁶ Ha
Ultra-precise	10⁻⁷ kcal/mol	1.593601437641 × 10⁻¹⁰ Ha

How ordering works

Bid. Choose your accuracy, a 30-, 60- or 90-day deadline, and your price. We’ll email you if we accept it. Nothing is charged until your proof is ready.
Proof. We compute your bounds and seal them with a zero-knowledge proof before you pay.
Payment. We email you an invoice, due on receipt.
Result. After payment, you receive the bounds and a second proof linking them to the sealed values.

If we can’t reach your accuracy by the deadline, you owe nothing. Full terms are in the Commercial Terms of Service.

Certify the ground-state energy

Cite this entry

Echeruo, C. U. (2026). Ready-to-use eight-electron eight-orbital active-space Hamiltonians for 125,999 small neutral molecules [Data set]. Zenodo. https://doi.org/10.5281/zenodo.23601240
Entry: Ethanol, PubChem CID 702, pcq702_6-31g_cas8e8o.fcidump, sha256 14199aece64925c7b73f7e65e42448d7a288ef6f837939a0ed4d159b58000cfe