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Record W1978683587 · doi:10.1021/jp9943631

Properties of Atoms in Molecules:  Group Additivity

2000· article· en· W1978683587 on OpenAlexaff
Richard F. W. Bader, David Bayles

Bibliographic record

VenueThe Journal of Physical Chemistry A · 2000
Typearticle
Languageen
FieldPhysics and Astronomy
TopicAdvanced Chemical Physics Studies
Canadian institutionsMcMaster University
Fundersnot available
KeywordsDelocalized electronTransferabilityChemistryGroup (periodic table)MoleculeElectronAdditive functionBenzeneComputational chemistryCrystallographyDensity functional theoryElectron pairPyridineChemical physicsAtomic physicsPhysicsOrganic chemistryMathematicsQuantum mechanics

Abstract

fetched live from OpenAlex

Every property of a molecule is given by the sum of the contributions from each of its constituent atoms or groups, the groups being defined as proper open systems. The observation of “experimental group additivty” requires that in addition to the properties of the groups being additive, the group and its properties be transferable from one molecule to another, different molecule. It is shown that such transferability of a group and its properties is in general, only apparent, being the result of compensatory transferability wherein the changes in the properties of one group are compensated for by equal but opposite changes in the properties of the adjoining group. These compensating changes are in some cases vanishingly small, but even when the energy changes are in excess of 20 kcal/mol, the experimental heat of formation is still predicted to be additive to within 0.1 kcal/mol. The operation of compensatory transferability is illustrated for the linear homologous series of hydrocarbons and polysilanes and for the formation of pyridine from fragments of benzene and pyrazine. The properties considered are the energy and the delocalization of the electrons, the former determined by the one-electron density matrix and the latter by the pair density. It is shown that the transferability of the degree of localization of the electrons to a given group, a property of the pair density, is a result of the conservation of the delocalization of its electrons over the remaining groups in the molecule. The results presented here emphasize the important observation that all the properties of a proper open system a functional group whether determined by the first-order density matrix, the pair density, or field-induced charge and current densities, are all functionally related to its form in real space, that is, to its distribution of charge.

Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.

How this classification was reachedexpand

Full frame machine prediction

Teacher imitation

Not calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.

metaresearch head score (Codex)0.001
metaresearch head score (Gemma)0.002
Version: metacan-v3-hybrid-931329e0061cValidation status: machine_predicted_unvalidated
Candidate categoriesnone
Consensus categoriesnone
DomainCandidate signal: none · Consensus signal: none
Study designCandidate signal: Bench or experimental · Consensus signal: none
GenreCandidate signal: Empirical · Consensus signal: Empirical
Teacher disagreement score0.004
Threshold uncertainty score0.013

Distilled classifier scores by category (both heads)

CategoryCodexGemma
Metaresearch0.0010.002
Meta-epidemiology (narrow)0.0000.000
Meta-epidemiology (broad)0.0000.001
Bibliometrics0.0010.000
Science and technology studies0.0010.005
Scholarly communication0.0020.002
Open science0.0010.002
Research integrity0.0000.001
Insufficient payload (model declined to judge)0.0040.000

Machine scores (provisional)

The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.

Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.

Opus teacher head0.008
GPT teacher head0.221
Teacher spread0.214 · how far apart the two teachers sit on this one work
Validation statusscore_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it

Classification

machine, unvalidated

Machine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.

The models applied no category: nothing in the taxonomy fit this work.
Study designBench or experimental
Domainnot available
GenreEmpirical

How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".

Quick stats

Citations131
Published2000
Admission routes1
Has abstractyes

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