Quantum Chemistry: State of the Art?

As a preparation for the upcoming launch of RealQM I ask chatGPT to summarise the state of the art of quantum chemistry as the essence of theoretical chemistry based on atom physics with key question: 

• Does textbook StdQM form a foundation of chemistry as the physics of molecules formed by chemically bonded atoms?

Does chatGPT give a fair correct assessment? chatGPT reports what is in the literature, but maybe not very explicitly. What would be the reaction from physicists vs chemists? The exponential computational complexity is not brought up, which requires drastic simplifications changing physics and numbers with effects difficult to quantify. 

chatGPT:

What StdQM does deliver (for atoms and molecules)

1. Well-defined mathematical models

StdQM provides:

• A many-body Schrödinger Hamiltonian for electrons and nuclei

• A mathematically precise spectral problem

• Conditions for self-adjointness, stability, and boundedness from below

This means:

The quantum model exists and is internally consistent.

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2. Atomic bound states and spectra

For atoms, StdQM delivers:

• Existence of discrete energy levels

• Correct qualitative and quantitative spectra

• Ionization thresholds and resonances

This is StdQM at its strongest:

Atoms are genuine quantum systems.

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3. Total energies (in principle)

StdQM determines:

• Ground-state energies

• Excitation energies

• Reaction energies (as differences)

These are global scalar quantities, accessible without spatial interpretation.

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4. Scattering and asymptotic processes

StdQM describes:

• Scattering cross sections

• Dissociation limits

• Long-time asymptotic behavior

Here again, the output is primarily spectral or asymptotic.

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5. Justification of approximations

StdQM can:

• Justify Born–Oppenheimer separation in asymptotic limits

• Explain why reduced models work

• Provide error estimates for approximations

Importantly:

StdQM explains why chemists’ models work, not what they mean physically.

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What StdQM does not deliver

6. Molecular structure

StdQM does not deliver:

• A theorem guaranteeing stable molecular geometry

• Unique equilibrium bond lengths or angles

• Classical molecular shape as a direct consequence of the wave function

Structure enters only via:

• Classical nuclei

• Potential energy surfaces

• Symmetry breaking assumptions

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7. Chemical bonds

StdQM does not provide:

• A bond operator

• A unique definition of “bond”

• An intrinsic quantum observable corresponding to bonding

Bonds are interpretive constructs, not quantum objects.

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8. Localization of electrons

StdQM does not deliver:

• Pointwise electron positions

• Intrinsic electron localization

• Distinct electrons occupying definite regions

Localization requires:

• Measurement postulates

• Classical limits

• Additional modeling choices

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9. Chemical identity

StdQM does not explain:

• Why molecules have persistent identity

• Why functional groups behave similarly across contexts

• Why chemistry is robust under perturbations

These are structural and dynamical facts, not spectral ones.

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10. Reaction mechanisms

StdQM does not deliver:

• Reaction pathways as physical processes

• Transition states as real entities

• Time-resolved chemical change

Mechanisms are reconstructed from:

• Energy surfaces

• Classical trajectories

• Human interpretation

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One-sentence summary

Standard quantum mechanics delivers energies, spectra, and asymptotic behavior for atoms and molecules, but it does not deliver molecular structure, bonding, or chemical processes as intrinsic physical facts.

Or, even more compact: StdQM

• predicts numbers; chemistry needs objects,
• is a powerful evaluative tool for chemistry,
• is not a constructive foundation of chemistry,
• can verify chemical models, but it does not create them. 
• is a qualified success in physics, but a failure as a foundation of chemistry. 
•  does not provide is a constructive procedure that starts from its axioms and ends with: molecule, bond, shape, reaction.

If the goal is to “Construct chemistry from first principles” then StdQM fails:

• Molecules are not constructed, only assumed.

• Structure is input, not derived.

• Bonds, shapes, and mechanisms are not quantum objects.

• Classical physics is silently reintroduced to make chemistry possible.

So as a reductionist program —chemistry = applied quantum mechanics —StdQM does not succeed.